Christmas is closing in, which means that families around the world are gearing up to celebrate the birth of Jesus. But when exactly was Jesus born?

Short answer: The Bible doesn’t tell us. God, in His infinite wisdom, didn’t find it needful to relay the exact date of Jesus’ birth to His faithful followers.

That said, it’s fun to travel down the rabbit hole and guess when it could have been. I will present a few theories, but it’s important to note that every day is a great day to celebrate the incarnation of Jesus, and no one can confirm with confidence when the nativity actually occurred.

Theory 1: November 13 (Earliest Proposed Date)

The earliest attempt to calculate the birth of Jesus comes from Clement of Alexandria’s 200 AD work Stromata:

“From the birth of Christ, therefore, to the death of Commodus are, in all, a hundred and ninety-four years, one month, thirteen days.” (Stromata, Book 1, Chapter 21)

Given that Commodus died on December 31, 192 AD, we can calculate the birth of Jesus according to Clement: November 18, 3 BC.

In this same document, however, Clement notes that there are many who disagree with him:

“There are those who have determined not only the year of our Lord’s birth, but also the day. And they say that it took place in the twenty-eighth year of Augustus, and in the twenty-five day of Pachon [May 20, 3 BC]…Others say that He was born on the twenty-fourth or twenty-fifth of Pharmuthi [April 19-20].”

It is unclear how these three dates were derived. And ultimately, none of these dates caught on, but all three would have been proposed early in Christian history.

Theory 2: December 25

Hippolytus of Rome was the first to suggest that Jesus was born on December 25. In his Commentary on Daniel in 204 AD, he wrote:

“For the first advent of our Lord in the flesh, when He was born in Bethlehem, was eight days before the Kalends of January [i.e., December 25], the fourth day [Wednesday], while Augustus was in his forty-second year… He suffered in the thirty-third year, eight days before the Kalends of March [March 25], the day of preparation, the eighteenth year of Tiberius Caesar.” (Commentary on Daniel, Book 4, Chapter 23.3)

The date of December 25 was chosen based on a Jewish tradition that righteous men entered the world and died on the same day:

“The Holy One, blessed is He, sits and fills the years of the righteous from day to day and from month to month, as it is written, ‘The number of your days I will fulfill’ (Exodus 23:26).” (Rosh Hashanah 11a)

Building from this tradition, it was reasoned that Jesus’ conception and death happened on the same day:

“For He is believed to have been conceived on the 25^th of March, upon which day also He suffered; so the womb of the Virgin, in which He was conceived, where no one of mortals was begotten, corresponds to the new grave in which He was buried, wherein was never man laid, neither before nor since. But He was born, according to tradition, upon December 25^th.” (De Trinitate, Book IV, Chapter 5)

Thus, within a few centuries after the resurrection, December 25^th was adopted as the traditional date of Jesus’ birth.

Theory 3: The Feast of Tabernacles (Tishri 15)

In recent years, another possibility has been conjectured—that Jesus was born during the autumn festival of Sukkot. This date makes much sense thematically. The Feast of Tabernacles (or Sukkot in Hebrew) celebrates God’s presence with mankind. Furthermore, the incarnation is described by John as a time when “the Word became flesh and tabernacled [Greek skenoo] among us” (John 1:14).

There is additional textual support. Luke’s gospel narrative uses parallel language to compare Zechariah and Elizabeth to Abraham and Sarah:

• Both are described as προβεβηκότες ἡμέραις—“well advanced in years” (Luke 1:7, Genesis 18:11)
• Sarah and Elizabeth are called στεῖρα—“barren” (Luke 1:7, Genesis 11:30)
• Zechariah and Elizabeth are described as ἦσαν δὲ δίκαιοι ἀμφότεροι ἐνώπιον τοῦ θεοῦ πορευόμενοι ἐν πάσαις ταῖς ἐντολαῖς καὶ δικαιώμασιν τοῦ κυρίου ἄμεμπτοι—“they were both righteous before God, walking in all the commandments and ordinances of the Lord blameless” (Luke 1:6). Just about every one of these words is lifted from the Abraham narrative (Genesis 15:6, 17:1, 24:40, Genesis 26:5).
• Both couples were visited by an angel who spoke of a miracle birth (Luke 1:11, Genesis 18)

Luke seems to want his audience to associate the birth of John with the birth of Isaac. And given that Isaac was said to be born during “the time of life” (Hebrew אֵלֶ֨יךָ֙ כָּעֵ֣ת חַיָּ֔ה)—a possible reference to Passover according to Rabbinic tradition (Rosh Hashanah 11a, 500 AD)—it is thought that John was born during Passover as well. And if John was born at Passover, Jesus was born six months later—during the Festival of Tabernacles in the fall.

The Temple Service of the Division of Abijah

In 1583, a French scholar named Joseph Scaliger proposed a new methodology for dating the birth of Jesus—one that didn’t rely on theological arguments and tradition but upon mathematical calculations.

From oft-overlooked scriptures to the writings of Josephus and the Talmud, we can assemble a collection of clues that can arguably narrow down the date on which Jesus was born:

• The Gospel of Luke tells us that Zechariah was a priest “of the division of Abijah” (Luke 1:5)
• We read in the Hebrew Scriptures that Abijah was the eighth division to serve in the temple (1 Chronicles 24:10)
• Zechariah lived in “the hill country of Judea” (Luke 1:39, 65)—somewhere between 4-20 miles from Jerusalem—indicating he would be able to arrive home on the same day he departed from the temple
• Josephus writes that each division served for one week—“one course should minister to God eight days, from sabbath to sabbath” (Antiquities of the Jews, Book 7.14.7)
• Josephus’ account lines up with the biblical testimony, suggests divisions began and ended their temple service on each Sabbath (2 Kings 11:5, 9; 2 Chronicles 23:8)
• A later rabbinic tradition from the Mishnah writes that “at three times during the year, all priestly watches are equal,” meaning they all serve in the temple during the three festivals (Mishnah Sukkah 5, Sukkah 55b)
• This same rabbinic tradition refers to “the priestly watch whose time is fixed,” indicating that each division served a “fixed” eight days (from Sabbath to Sabbath), uninterrupted by the arrival of additional divisions during the feasts
• Jewish tradition states that the first division—Jehoiarib—was serving when the Temple was destroyed on Sunday, the 9^th of Av in 70 AD (Taanit 29a, Jerusalem Talmud Taanit 4:5, Seder Olam Rabbah 30)

Using these datapoints assuming these later sources are accurate, it becomes possible to reconstruct when Zechariah would have been serving at the temple, giving us a few dates when he would have returned home to conceive a child with Elizabeth.

How the Biblical Calendar Functioned

The biblical year typically included twelve months, where each month was based upon the moon cycle and the first day of each month would begin at the first sight of the crescent moon. Since the moon cycle lasts 29.53 days, a biblical year would last between 354 and 355 days.

This falls about ten days short of a solar year (365.2425 days), meaning that—if left unchecked—each biblical year would begin ten days sooner than the previous year, and Passover (the spring feast) drift be celebrated in the dead of winter after only ten years. Thus a leap month was added about every three years to offset this drift, resulting in a thirteen-month year lasting 383 to 384 days.

The modern Jewish calendar was implemented in around 924 AD and attempts to mathematically replicate the ancient method by fixing month lengths and leap months to a repeating cycle rather than the movements of the moon and sun. The result is close to the original method by not precise—month lengths can range from 353-355 and 383-385 days, and a leap month is occasionally added to the wrong month (this is currently true—however, there is a slight drift, and thousands of years in the future the calendar will sometimes be off by months at a time).

For the purposes of our calculations, we will provide both the dates of the ancient biblical calendar and the modern Jewish calendar when they differ and notate this adjustment accordingly.

When Did the Division of Abijah Serve?

As stated above, the biblical account and historical records confirm that priests served in the temple in fixed eight-day watches (from Saturday to Saturday). These watches would not be interrupted by the festivals—rather additional priests would arrive to offer additional support during these times. This lack of interruptions is confirmed by the aforementioned timing of first division’s (Jehoiarib’s) service in 70 AD, which began on Shabbat (Saturday), Av 8, 70 AD (August 4)—the nineteenth week of the year. Since the year can be anywhere from 50 ½ weeks to 55 weeks (would doesn’t divide neatly into 24 divisions), this would result in a 2.5-7 week shift every week—e.g., if the tribe of Abijah began service on the 14^th sabbath in one year, they might begin service on the 11^th of the following year (or 7^th during a leap year).

Using Av 9 (August 4), 70 AD as our anchor point, we can count backwards 24 weeks at a time to determine when each division would have been serving in the years leading up to Jesus’ birth. Most scholars agree that Jesus was born between 7 BC and 4 BC, so we will examine 8 BC to 3 BC as possible birthyears.

The table below shows the dates (both Julian, Ancient Biblical, and Modern Jewish) that the division of Abijah would have served, using an uninterrupted, shifting calendar:

Table 1: Abijah Service (Uninterrupted Shifting Calendar)

Division of Abijah Service Begins		Division of Abijah Service Ends
Tammuz 24	Jul. 13, 9 BC	Av 2	Jul. 20, 9 BC
Tebet 14	Dec. 28, 9 BC	Tebet 21	Jan. 4, 8 BC
Tammuz 6 (ancient) Sivan 5 (modern)	Jun. 14, 8 BC	Tammuz 13 (ancient) Sivan 12 (modern)	Jun. 21, 8 BC
Kislev 27 (ancient) Cheshvan 25 (modern)	Nov. 29, 8 BC	Tebet 6 (ancient) Kislev 3 (modern)	Dec. 6, 8 BC
Iyar 17	May 16, 7 BC	Iyar 24	May 23, 7 BC
Cheshvan 8	Oct. 31, 7 BC	Cheshvan 15	Nov. 7, 7 BC
Nisan 29	Apr. 17, 6 BC	Iyar 6	Apr. 24, 6 BC
Tishri 20	Oct. 2, 6 BC	Tishri 27	Oct. 9, 6 BC
Nisan 12 (ancient) II Adar 10 (modern)	Mar. 19, 5 BC	Nisan 19 (ancient) II Adar 17 (modern)	Mar. 26, 5 BC
Tishri 2 (ancient) Av 30 (modern)	Sep. 2, 5 BC	Tishri 9 (ancient) Elul 7 (modern)	Sep. 9, 5 BC
Shebet 20	Feb 17, 4 BC	Shebet 27	Feb. 24, 4 BC
Av 11	Aug. 4, 4 BC	Av 18	Aug. 11, 4 BC
Shebet 3	Jan. 19, 3 BC	Shebet 10	Jan. 26, 3 BC
Tammuz 23	Jul. 6, 3 BC	Av 1	Jul. 13, 3 BC
Tebet 14	Dec. 21, 3 BC	Tebet 21	Dec. 28, 3 BC

Alternatively, some have recently proposed the possibility that the first division would have always served during the first week of the year, the second division the second week, and so on. Proponents of this method also surmise that during the feasts—when all divisions were serving—the weekly rotation would have been pushed back. When one of the three major feasts rolled around, this service would be pushed back accordingly. If true, various divisions would have always served during the exact same time every year—e.g., the tenth division would always serve between days 73 and 79 of the calendar (Sivan 14 to Sivan 20), having started counting on Nisan 1 and pushing back eight days for Passover/Unleavened Bread and one day for Weeks.

There are a few issues with this methodology. For one, it doesn’t align with any part of the historical record. Additionally, 24 divisions each serving two week-long shifts plus an additional 17 days for the feasts falls 1-2 days short of the full year. Which division serves these additional few days? And in the event of a leap year, there could be as many as 32 extra days to make up. How are these additional days covered?

Adopting a possible “non-shifting” division cycle rejects the biblical account, historical records, and Jewish tradition, and creates more problems without bringing clarity. Regardless, we will include these non-shifting dates in our calculations to provide a thorough investigation of possible birthdates:

Table 2: Abijah Service (Non-Shifting Calendar)

Division of Abijah Service Begins		Division of Abijah Service Ends
Iyar 27	May 18, 9 BC	Sivan 4	May 24, 9 BC
Cheshvan 28	Nov. 12, 9 BC	Kislev 5	Nov. 18, 9 BC
Iyar 27	May 7, 8 BC (ancient) Jun. 7, 8 BC (modern)	Sivan 4	May 13, 8 BC (ancient) Jun. 13, 8 BC (modern)
Cheshvan 28	Nov. 1, 8 BC (ancient) Dec. 2, 8 BC (modern)	Kislev 5	Nov. 7, 8 BC (ancient) Dec. 8, 8 BC (modern)
Iyar 27	May 26, 7 BC	Sivan 4	Jun. 1, 7 BC
Cheshvan 28	Nov. 20, 7 BC	Kislev 5	Nov. 26, 7 BC
Iyar 27	May 15, 6 BC	Sivan 4	May 21, 6 BC
Cheshvan 28	Nov. 9, 6 BC	Kislev 5	Nov. 15, 6 BC
Iyar 27	May 3, 5 BC (ancient) Jun. 3, 5 BC (modern)	Sivan 4	May 9, 5 BC (ancient) Jun. 9, 5 BC (modern)
Cheshvan 28	Oct. 28, 5 BC (ancient) Nov. 28, 5 BC (modern)	Kislev 5	Nov. 3, 5 BC (ancient) Dec. 4, 5 BC (modern)
Iyar 27	May 24, 4 BC	Sivan 4	May 30, 4 BC
Cheshvan 28	Nov. 18, 4 BC	Kislev 5	Nov. 24, 4 BC
Iyar 27	May 12, 3 BC	Sivan 4	May 18, 3 BC
Cheshvan 28	Nov. 6, 3 BC	Kislev 5	Nov.12, 3 BC

Finally, all divisions would have served during the three major feasts:

Table 3: Feast Service

	Service Begins		Service Ends
Passover	Nisan 14	Apr. 5, 9 BC	Nisan 21	Apr. 12, 9 BC
Weeks	Sivan 6	May 26, 9 BC	Sivan 6	May 26, 9 BC
Tabernacles	Tishri 15	Sep. 30, 9 BC	Tishri 21	Oct. 7, 9 BC
Passover	Nisan 14	Mar. 25, 8 BC (ancient) Apr. 25, 8 BC (modern)	Nisan 21	Apr. 1, 8 BC (ancient) May 2, 8 BC (modern)
Weeks	Sivan 6	May 15, 8 BC (ancient) Jun. 15, 8 BC (modern)	Sivan 6	May 15, 8 BC (ancient) Jun. 15, 8 BC (modern)
Tabernacles	Tishri 15	Sep. 19, 8 BC (ancient) Oct. 20, 8 BC (modern)	Tishri 21	Sep. 26, 8 BC (ancient) Oct. 27, 8 BC (modern)
Passover	Nisan 14	Apr. 13, 7 BC	Nisan 21	Apr. 20, 7 BC
Weeks	Sivan 6	Jun. 3, 7 BC	Sivan 6	Jun. 3, 7 BC
Tabernacles	Tishri 15	Oct. 8, 7 BC	Tishri 21	Oct. 15, 7 BC
Passover	Nisan 14	Apr. 2, 6 BC	Nisan 21	Apr. 9, 6 BC
Weeks	Sivan 6	May 23, 6 BC	Sivan 6	May 23, 6 BC
Tabernacles	Tishri 15	Sep. 27, 6 BC	Tishri 21	Oct. 4, 6 BC
Passover	Nisan 14	Mar. 21, 5 BC (ancient) Apr. 21, 5 BC (modern)	Nisan 21	Mar. 28, 5 BC (ancient) Apr. 28, 5 BC (modern)
Weeks	Sivan 6	May 11, 5 BC (ancient) Jun. 11, 5 BC (modern)	Sivan 6	May 11, 5 BC (ancient) Jun. 11, 5 BC (modern)
Tabernacles	Tishri 15	Sep. 15, 5 BC (ancient) Oct. 16, 5 BC (modern)	Tishri 21	Sep. 22, 5 BC (ancient) Oct. 23, 5 BC (modern)
Passover	Nisan 14	Apr. 11, 4 BC	Nisan 21	Apr. 18, 4 BC
Weeks	Sivan 6	Jun. 1, 4 BC	Sivan 6	Jun. 1, 4 BC
Tabernacles	Tishri 15	Oct. 6, 4 BC	Tishri 21	Oct. 13, 4 BC
Passover	Nisan 14	Mar. 30, 3 BC	Nisan 21	Apr. 6, 3 BC
Weeks	Sivan 6	May 20, 3 BC	Sivan 6	May 20, 3 BC
Tabernacles	Tishri 15	Sep. 24, 3 BC	Tishri 21	Oct. 1, 3 BC

Between these various methods, we arrive at roughly 36 dates from 9 BC to 3 BC for when Zechariah returned home (with an alternate 14 days if we substitute the historical method of uninterrupted, eight-day shifts with an assumed non-shifting calendar; and an alternate 14 days if we substitute the ancient biblical calendar with the modern Jewish calendar).

 Calculating Jesus’ Birth Date from Zechariah’s Service

It bears repeating that the gospel authors do not specify the date of Jesus’ birth. Thus, the text does not provide specific details that would allow us to pinpoint the exact moment of His birth. But in our recreational pursuit of this birthdate, we can utilize several clues to hone in on a possible solution.

John was conceived the day after Zechariah returned home

• Luke’s gospel account tells us that Zechariah left the temple “as soon as the days of his service were completed” (Luke 1:23), and that “after those days his wife Elizabeth conceived” (v. 24).
• Thus we can assume that John was conceived 1 day after Zechariah’s return, with a possible window of 1 to 7 days.

Mary conceived 5¾ months after Elizabeth conceived

• We read that Elizabeth “hid herself five months” (Luke 1:24) after she conceived.
• Furthermore, Mary was visited by the angel “in the sixth month” (vv. 26, 36) of Elizabeth’s pregnancy, indicating this took place between 5-6 months after Elizabeth’s conception.
• After the angelic visitation, Mary arose “in those days and went into the hill country [of Judah] with haste” (v. 39), roughly a five-to-seven-day journey.
• When Mary first arrived and greeted Elizabeth (v. 41), baby John leaped in the womb and Elizabeth declared, “Blessed is the fruit of your [Mary’s] womb” (v. 42), indicating May was already pregnant.
• Mary remains with Elizabeth “about three months, and returned to her house” (v. 56) before the birth of John, again reinforcing that Mary arrived before a full six months of Elizabeth’s pregnancy.
• Thus we can assume that Jesus was conceived 170 days after John (29.53-day month times 5¾ months), with a possible window of 162 to 177 days (5½ to 6 months).

Jesus was born full-term

• Finally, Elizabeth’s pregnancy is recorded as being “full time” (v. 56) and Jesus was born when “the days were completed” (Luke 2:6), meaning both pregnancies were full-term.
• This is confirmed by the timing related to Elizabeth’s pregnancy: 5.5 months at Mary’s conception, Mary’s 1-week trip to Judea, Mary’s 3-month stay, and Mary’s 1-week trip home is exactly nine months.
• Thus we can assume that Mary was pregnant for 266 days (a full-term pregnancy), with a possible window of 259 to 273 days (one week early to one week late).

Based on these markers, Jesus was born 437 days after Zechariah returned home, with a possible window of 422 to 457 days (a two-week buffer before and a three-week buffer after). A range of 35 days (457 minus 422), applied to roughly 8 different possible starting points will admittedly cover most of the calendar. In fact, this allowable range will cover an average of seven months per calendar year. Below we will examine which of our theoretical dates (April 19-20, Mat 20, November 18, December 25, and Tishri 15) fit into this generous range of dates.

Table 4: Possible Dates of Jesus’ Birth (Feasts and Uninterrupted Shifting Calendar)

Date of Birth		Earliest Date of Birth		Latest Date of Birth
Tammuz 15	Jun. 23, 8 BC	Sivan 30	Jun. 8, 8 BC	Av 6	Jul. 13, 8 BC
Av 30	Aug. 6, 8 BC	Av 15	Jul. 22, 8 BC	Elul 20	Aug. 26, 8 BC
Tishri 26	Sep. 30, 8 BC	Tishri 11	Sep. 15, 8 BC	Cheshvan 16	Oct. 20, 8 BC
Tebet 16	Dec. 18, 8 BC	Tebet 1	Dec. 3, 8 BC	Shevet 7	Jan. 7, 7 BC
II Adar 16	Mar. 17, 7 BC	II Adar 1	Mar. 2, 7 BC	Nisan 7	Apr. 6, 7 BC
Sivan 15	Jun. 12, 7 BC	Iyar 29	May 28, 7 BC	Tammuz 5	Jul. 2, 7 BC
Tammuz 29	Jul. 26, 7 BC	Tammuz 14	Jul. 11, 7 BC	Av 20	Aug. 15, 7 BC
Elul 7	Sep. 1, 7 BC	Av 22	Aug. 17, 7 BC	Elul 27	Sep. 21, 7 BC
Kislev 16	Dec. 7, 7 BC	Kislev 1	Nov. 22, 7 BC	Tebet 6	Dec. 27, 7 BC
Shebet 28	Feb. 16, 6 BC	Shebet 13	Feb. 1, 6 BC	Adar 18	Mar. 8, 6 BC
Tammuz 15	Jul. 1, 6 BC	Sivan 30	Jun. 16, 6 BC	Av 6	Jul. 21, 6 BC
Av 19	Aug. 3, 6 BC	Av 4	Jul. 19, 6 BC	Elul 9	Aug. 23, 6 BC
Av 30	Aug. 14, 6 BC	Av 15	Jul. 30, 6 BC	Elul 20	Sep. 3, 6 BC
Tebet 15	Dec. 26, 6 BC	Kislev 30	Dec. 11, 6 BC	Shebet 16	Jan. 15, 5 BC
Shebet 9	Jan. 18, 5 BC	Kislev 23	Jan. 3, 5 BC	Shebet 29	Feb. 7, 5 BC
Tammuz 15	Jun. 19, 5 BC	Sivan 30	Jun. 4, 5 BC	Av 6	Jul. 9, 5 BC
Av 1	Jul. 4, 5 BC	Tammuz 15	Jun. 19, 5 BC	Av 21	Jul. 24, 5 BC
Av 30	Aug. 2, 5 BC	Av 15	Jul. 18, 5 BC	Elul 20	Aug. 22, 5 BC
Tebet 16	Dec. 14, 5 BC	Tebet 1	Nov. 29, 5 BC	Shevet 7	Jan. 3, 4 BC
Tebet 21	Dec. 19, 5 BC	Tebet 6	Dec. 4, 5 BC	Shevet 12	Jan. 8, 4 BC
Sivan 11	Jun. 6, 4 BC	Iyar 25	May 22, 4 BC	Tammuz 1	Jun. 26, 4 BC
Sivan 13	Jun. 8, 4 BC	Iyar 27	May 24, 4 BC	Tammuz 3	Jun. 28, 4 BC
Tammuz 27	Jul. 22, 4 BC	Tammuz 12	Jul. 7, 4 BC	Av 18	Aug. 11, 4 BC
Cheshvan 1	Nov. 20, 4 BC	Cheshvan 15	Nov. 5, 4 BC	Kislev 21	Dec. 10, 4 BC
Kislev 14	Dec. 3, 4 BC	Cheshvan 28	Nov. 18, 4 BC	Tebet 5	Dec. 23, 4 BC
Iyar 22	May 7, 3 BC	Nisan 6	Apr. 22, 3 BC	Sivan 13	May 27, 3 BC
Tammuz 16	Jun. 29, 3 BC	Tammuz 1	Jun. 14, 3 BC	Av 7	Jul. 19, 3 BC
Elul 1	Aug. 12, 3 BC	Av 16	Jul. 28, 3 BC	Elul 21	Sep. 1, 3 BC
Cheshvan 13	Oct. 22, 3 BC	Tishri 28	Oct. 7, 3 BC	Kislev 4	Nov. 11, 3 BC
Tebet 17	Dec. 24, 3 BC	Tebet 2	Dec. 9, 3 BC	Shebet 8	Jan. 13, 2 BC
Nisan 4	Apr. 8, 2 BC	II Adar 18	Mar. 24, 2 BC	Nisan 24	Apr. 28, 2 BC
Sivan 15	Jun. 17, 2 BC	Iyar 29	Jun. 2, 2 BC	Tammuz 5	Jul. 7, 2 BC
Tammuz 29	Jul. 31, 2 BC	Tammuz 14	Jul. 16, 2 BC	Av 20	Aug. 20, 2 BC
Elul 24	Sep. 23, 2 BC	Elul 9	Sep. 8, 2 BC	Tishri 15	Oct. 13, 2 BC
Kislev 15	Dec. 12, 2 BC	Cheshvan 30	Nov. 27, 2 BC	Tebet 5	Jan. 1, 1 BC
Adar 14	Mar. 9, 1 BC	Shebet 29	Feb. 23, 1 BC	Nisan 5	Mar. 29, 1 BC

Between the years 8 BC and 3 BC, we find the following results:

Clement’s Estimation of November 18, 3 BC:

• November 18, 3 BC does not fall within the 35-day window. Jesus’ birth would have to have happened 27 days after our predicted date.
• However, November 18, 4 BC, is a plausible date, occurring only two days earlier than our predicted date of November 20, 4 BC (based on the division of Abijah’s rotational service ending on September 9/Tishri 9, 5 BC).

Clement’s Recording of May 20:

• May 20, 3 BC is only 13 days after our predicted date of May 7, 3 BC (based on Abijah’s rotation service ending on February 24/I Adar 29, 4 BC), making it a possible date.

Clement’s Recording of April 19-20:

• April 19-20 never fell within our window of possible dates.
• The closest this date ever came was on April 20/Nisan 5, 3 BC, where it occurred 17 days before our predicted date (meaning Mary would have needed to deliver Jesus roughly 17 days earlier than expected).

Feast of Tabernacles:

• The only year Tishri 15 fell within the plausible window was 8 BC. That year, the Feast of Tabernacles began on September 19, 8 BC, only 11 days before our predicted date of September 30 (based on Abijah’s rotational service ending on July 20/Tammuz 2, 9 BC). This eleven-day gap could be made up by some combination of Mary visiting Elizabeth earlier than assumed, Jesus being born a few days early, and Jesus’ birth occurring during the latter end of Tabernacles rather than on the first day.
• It should be noted that most scholars place Jesus’ birth between 7 BC and 4 BC, making a birthdate of Tishri 15/September 19, 8 BC less plausible.
• For the remaining five years (7 BC-3 BC), the closest that the Feast of Tabernacles comes to our 35-day window is 28 days early to 37 days late—and the 28-day date occurs in 3 BC, too late for Jesus’ birth, according to most scholars.

Christmas:

• During the six years of 8 BC to 3 BC, December 25 fell within our 35-day window five times—twice within 1 day and an additional two years within 1 week.
• Our predicted date of December 18, 8 BC is only seven days before Christmas. With this timing, Jesus’ conception would have occurred on Nisan 16/March 27—during the Feast of Passover.
• Our predicted date of December 7, 7 BC is only 18 days before Christmas.
• Our predicted date of December 26, 6 BC is only 1 day after Christmas—almost an exact match! Additionally, this dating would place Jesus’ conception on Nisan 16/April 4—during the Feast of Passover.
• Our predicted date of December 19, 5 BC is only 6 days before Christmas. With this timing, Jesus’ conception would have occurred on Nisan 17/March 24—during the Feast of Passover.
• Christmas Day in 4 BC (December 3) is our least likely date, falling 22 days early.
• Our predicted date of December 24, 3 BC is only one day before Christmas—again, almost an exact match! Additionally, this dating would place Jesus’ conception on Nisan 17/April 2—during the Feast of Passover.

For the sake of thoroughness, we also examined the alternative dates for the division of Abijah, should we reject the testimony of 2 Chronicles, Josephus, and rabbinic tradition and create a non-shifting rotational cycle.

Table 5: Possible Dates of Jesus’ Birth (Non-Shifting Calendar)

Date of Birth		Earliest Date of Birth		Latest Date of Birth
Av 28	Aug. 4, 8 BC	Av 13	Jul. 20, 8 BC	Elul 18	Aug. 24, 8 BC
Shevet 29	Jan. 29, 7 BC	Shevet 14	Jan. 14, 7 BC	I Adar 19	Feb. 18, 7 BC
Tammuz 27	Jul. 24, 7 BC	Tammuz 12	Jul. 9, 7 BC	Av 18	Aug. 13, 7 BC
Tebet 28	Jan. 18, 6 BC	Tebet 13	Jan. 3, 6 BC	Shebet 19	Feb. 7, 6 BC
Av 28	Aug. 12, 6 BC	Av 13	Jul. 28, 6 BC	Elul 18	Sep. 1, 6 BC
Shebet 28	Feb. 6, 5 BC	Shebet 13	Jan. 22, 5 BC	Adar 18	Feb. 26, 5 BC
Av 28	Jul. 31, 5 BC	Av 13	Jul. 16, 5 BC	Elul 18	Aug. 20, 5 BC
Shevet 29	Jan. 25, 4 BC	Shevet 14	Jan. 10, 4 BC	I Adar 19	Feb. 14, 4 BC
Tammuz 25	Jul. 20, 4 BC	Tammuz 10	Jul. 5, 4 BC	Av 16	Aug. 9, 4 BC
Tebet 27	Jan. 14, 3 BC	Tebet 12	Dec. 30, 4 BC	Shebet 18	Feb. 3, 3 BC
Av 29	Aug. 10, 3 BC	Av 14	Jul. 26, 3 BC	Elul 19	Aug. 30, 3 BC
Shebet 30	Feb. 4, 2 BC	Shebet 15	Jan. 20, 2 BC	I Adar 20	Feb. 24, 2 BC
Tammuz 27	Jul. 29, 2 BC	Tammuz 12	Jul. 14, 2 BC	Av 18	Aug. 18, 2 BC
Tebet 27	Jan. 23, 1 BC	Tebet 12	Jan. 8, 1 BC	Shebet 18	Feb. 12, 1 BC

The 35-day window based upon these new dates do not align with any of the aforementioned traditions:

• Clement’s November 18 estimation never gets closer than 61 days early.
• The May 20 and April 19-20 estimations are never closer than 61 days early and 73 days late, respectively.
• Christmas is consistently 20 to 43 days before any of these dates.
• The dates for the Feast of Tabernacles (Tishri 15) are always 45 to 78 days late, roughly 1½ and 2½ months.

Conclusion

Luke likely did not intend for his mention of Zechariah’s membership in the division of Abijah to be used to determine the date of Jesus’ birth—if Luke wanted us to know the exact date, he would have told us. Many assumptions need to be made in order to determine a plausible date from these details, and any unknown alteration to these patterns (e.g., what if the high priest postponed a division’s service dates, what if Passover were delayed for unexpected reasons one year, etc.) would render our calculations useless.

Having said that, if we appropriate the minor fact of Zechariah’s membership in the division of Abijah to deduce the dating of Jesus’ birth, most of Clement’s cited dates do not fit. May 20, 3 BC comes close to fitting, but most scholars agree Jesus would have been born between 7 BC and 4 BC, so this date is unlikely.

The dates of the Feast of Tabernacles also do not fit neatly into this pattern. September 19, 8 BC was the only one to match Abijah’s service, but this falls before the aforementioned 7 BC that most scholars agree upon. The remaining dates for Tabernacles fall between 4 and 5 weeks late. These could work if we assume that it took over a month for Elizabeth to conceive, but given the supernatural circumstances of her conception, this is also unlikely.

Surprisingly, Christmas is the best fit given the data. Four of the five years between 7 BC and 4 BC land near our calculated date—and three of those place Jesus’ conception at the same time as His eventual death, just as Hippolytus and Augustine surmised.

 When was Jesus actually born?

Thematically, the Feast of Tabernacles tells the best story. But if we use Luke’s casual reference to the division of Abijah, we find Christmas Day to be a stronger contender. And given several thousand years of historical precedent, it is a good thing to join with 2.3 billion Christians around the world during the Christmas season and rejoice in the birth of our Lord and Savior.

So declare Jesus’ incarnation every December. Declare it in the fall. Declare it in the spring and in the summer. Because Jesus—the perfect God-Man—is alive every day.