The Holy Catholic Church observes, not dogmatically defined, the 25th day of every December as the birthdate of the Savior, Lord Jesus Christ. But, why December 25?
In the Old Testament, prophet Haggai prophesied: “And I will shake all nations, and the desire of all nations shall come: and I will fill this house with glory, saith the LORD of hosts. The silver is mine, and the gold is mine, saith the LORD of hosts. The glory of this latter house shall be greater than of the former, saith the LORD of hosts: and in this place will I give peace, saith the LORD of hosts. In the four and twentieth day of the ninth month, in the second year of Darius, came the word of the LORD by Haggai the prophet, saying” (Haggai 2:7-10). Take note that Haggai 2:7 prophesied that “The desire of all nations will come”. Who is the desire of all nations? THE MESSIAH. The word of the Lord come on the four and twentieth of the ninth month, and when will this be? Remember that the Jewish Calendar starts in the month of Nisan (March-April). So, from Nisan (March-April), the 9th month falls to DECEMBER. Thus, following this prophecy, the Messiah came into the House of God (cf. 1 Timothy 3:15) on 24th of December, in accordance to the Jewish custom that a day is counted from setting to setting of the sun. Hence, December 25th starts from the setting of the sun on December 24th up to the setting of the sun on the following day, December 25th.
Furthermore, in Luke 2:1,23, the Lord was on the threshold of His 30th birthday when baptized during the 15th year of Tiberius before beginning His public ministry. Note that the 15th year of Tiberius was the calendar year AD 29 and the Jewish law and convention required men to be 30 years old before making disciples and undertaking active public teaching.
Since Jesus was 29 going to 30 years old in AD 29, He would have been born in 2 BC. This date is also given by many church fathers, who say Jesus was born in the 42nd (regnal) year of Emperor Augustus. A person born in 2 BC would have turned 30 years old before December 31, AD 29. Thus, Jesus would have turned 30 years old sometime after His baptism but before December 31st, and only then begun public ministry. St. Irenaeus, bishop of Lugdunum in Gaul, wrote: “For how could he have had disciples, if He did not teach? And how could He have taught, unless He had reached the age of a Master? For when He came to be baptized, He had not yet completed thirty years of age (for thus Luke, who has mentioned His years, has expressed it: ‘Now Jesus was, as it were, beginning to be thirty years old,’ when He came to be baptized).”
Following His fast and temptation, Jesus returned to John at Bethabara where He made His first disciples (Andrew, Peter, Phillip, and Nathaniel). The disciples call Him “Rabbi,” implying that Jesus was already 30 years old. Seven days following His return to John, Jesus attended a wedding in Cana of Galilee where He manifested his glory to his disciples. This miracle has been commemorated from the earliest times by the feast of Epiphany on January 6th. Reckoning backward seven days from January 6th would lead to December 31st. This is the point at which Jesus would have returned to John, having already turned 30 years old. From this, it can be concluded that Jesus was born in 2 BC and thus turned 30 years old before the end of the Julian year. It can also be said that His birthday would have fallen on or near December 25th.
Now, to determine the date as to when the Lord was born, consider the length of His public teaching. Jesus had a 3 ½ year ministry. He was crucified on Nisan 15 (April 2), AD 33. Reckoning backward 3 ½ years from Jesus’ crucifixion would lead to Heshvan 15 (November 8th), AD 29. Now, based upon a Heshvan 15 (November 8th) baptism of the Lord, there would have been 53 days remaining to the calendar year in which Jesus’ birthday occurred.
Also note that Jesus undertook a 40-day fast in preparation for His ministry. This brings to December 18, AD 29 (November 8 + 40 = December 18). In final preparation for His ministry, Jesus’ fast was followed by a period of temptation. Allow seven days in which this was accomplished, this will lead to December 25th. If Jesus’ fast and temptation, and 30th birthday were threshold events, He had to cross before beginning His ministry. It would make no sence for Jesus, having reached the age of a teacher, to errect a barrier to beginning His life’s work by undertaking an extended fast. Hence, it is most likely that His fast and temptation were so timed at to anticipate His birthday and that Jesus’ birthday intersected that point where His fast and temptation concluded. If so, Jesus birthday would have been December 25th.
On the other hand, the Lord’s birthdate can also be evidenced by the priestly courses as stated in the Sacred Scripture. Remember that there were 24 courses of priests that served in the temple twice annually, plus such additional weeks necessary to fill out the year. The names of the courses according to their father’s houses are given in I Chronicle 24:7-18. The two courses that concern here are Jehoiarib, the first, and Abijah, the eighth.
Zechariah, the father of John the Baptist, belonged to the course of Abijah, and was serving in the temple when Gabriel announced that Elizabeth, Zechariah’s wife, would conceive. John was six months older than our Lord. If it can once be determined when Zechariah was serving and John conceived, it can also be identified when Christ would have been born 15 odd months later.
Rabbi Yose ben Halafta, who was active 80 years after the event, reported that the course of Jehoiarib was serving the 9th of Ab, when the temple was destroyed by the Romans. Assuming the courses advanced one step annually to fulfill 24 years when the courses would begin anew, Jehoiarib would have been in its 21st year of the 24-year cycle that began AD 50. Reckoning backward in 24-year periods, the cycle Zechariah was serving would have consisted in the years 23 BC to AD 1. Counting forward from 23 BC to 3 BC when John would have been conceived, the course of Abijah served the weeks of Nisan 14-20 (March 28-April 3) and Elul 27-Tishri 4 (September 5-11).
Scientifically, women are fertile about seven days of a 28 day cycle. Normal gestation is 38 weeks for a woman to come to full term. Assuming Elizabeth conceived toward the end of the first month Zechariah completed his ministry, or about Tishri 26-Heshvan 2 (October 3-9), John would have been born 38 weeks later at Tammuz 20-26 (June 20-26), 2 BC. Reckoning six months (26 weeks) more, Jesus would have been born the week of Tebet 26-Shebat 3, which answers to December 21-27.
Lastly, dating the Savior’s birth can also be traced through the death of Herod and the visit of the Magi. About the time of Jesus’ birth, it was rumored that Herod the Great had died. Certain Jews seized the opportunity to rebel, removing the Roman eagle that adorned the temple gate. For this crime, Herod had the leaders burned alive. The Jewish historian Josephus reports that the night of the execution, there was a lunar eclipse. Astronomers date this eclipse to January 10, 1 BC.
Forty-days after the birth of Christ, the holy family made the required sacrifices at the temple for Mary and baby Jesus, and then returned home to Nazareth in Galilee. Several weeks passed and the Magi arrived at Jerusalem, seeking the Christ-child. Having sounded the scribes and elders of the Jews where Christ was to be born, Herod sends the Magi to Bethlehem, requesting that they bring him word when they have found the child.
Interposed by Heaven, the star that the Magi had seen in the east wondrously reappears, leading them to the child who by now is at Nazareth, not Bethlehem. Warned that Herod will seek the child to destroy him, the holy family flees to Egypt and the Magi return home another way. Herod, whose health is rapidly deteriorating, receives permission from Caesar Augustus to deal with his son Antipater as he sees best, including death. Antipater is in the palace prison for treason, seeking to poison Herod and accede the throne.
Shortly before Passover 1 BC, Herod tries to kill himself with a small paring knife; the palace is filled with crying and screams. It is rumored that the king has died. These rumors reach Antipater in the palace prison who attempts to bribe the jailor to release him with promise of rewards. The jailor reports this to Herod, who in a rage orders Antipater slain.
History records that, at the same time Antipater is slain, Herod ordered the Slaughter of the Innocents. According to Macrobius, when Augustus learned that Antipater had been executed during the Slaughter of the Innocents, he remarked “It is better to be Herod’s hog than his son.”
Herod survived Antipater by only five days, dying sometime before Passover 1 BC. The fact that history joins the Slaughter of the Innocents to the execution of Antipater shows that the Magi arrived sometime after the holy family had returned to Nazareth, a few weeks before Passover in 1 BC. Considering that the Magi arrived several weeks after the holy family returned home, then reckon backward 40 days more for the period before sacrifices were made for Mary and the baby at the temple, this will place Jesus’ birth near the traditional date of December 25th.
St. Hyppolytus of Rome, who explains in his Commentary on the book of Daniel (ca. AD 204) that the Lord’s birth was believed to have occurred on that day: “For the first advent of our Lord in the flesh, when he was born in Bethlehem, was December 25th, Wednesday, while Augustus was in his forty-second year, but from Adam, five thousand and five hundred years. He suffered in the thirty-third year, March 25th, Friday, the eighteenth year of Tiberius Caesar, while Rufus and Roubellion were Consuls.” Note that his reference to Adam can be understood in light of his another writings, the Chronicon, where he explains that Jesus was born nine months after the anniversary of Creation. According to his calculations, the world was created on the vernal equinox, March 25, which would mean Jesus was born nine months later, on December 25.
Based on the evidences presented above, the Church indeed never chose December 25th to christianize paganism such as Saturnalia, Sol Invictus, and Mithras; but she chose it as the Holy Spirit dictates. The truth is: whatever date that the Holy Catholic Church would choose for Christ’s birth, the enemies of the Church would still look for ways to attack it and associate it with pagan traditions because that’s how Satan works.
In his book, Spirit of the Liturgy, Pope-Emeritus Benedict XVI explains:
“The claim used to be made that December 25 developed in opposition to the Mithras myth, or as a Christian response to the cult of the unconquered sun promoted by Roman emperors in the third century in their efforts to establish a new imperial religion. However, these old theories can no longer be sustained. The decisive factor was the connection of creation and Cross, of creation and Christ’s conception (p. 105-107).”
BEHOLD, THE KING IS BORN. GOD IS TRULY WITH US!