Calculating the Date of the Nativity of Our Lord

by Sean M. Wright

North Texas Catholic

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“Quando Christus natus erat de Beatissima Maria Virgine?” asked several Christian historians and theologians living in the Roman Empire during the first 300 years of the Christian era. Over the centuries many Christians still ask: “When was Christ born of the Most Blessed Virgin Mary?”

The Church, then as now, was more concerned with celebrating Christ’s Death and Resurrection as the central flashpoints of history. Writing around the year 190, both Tertullian, the Roman attorney and priest, and St. Irenaeus, bishop of Lyons, compiled lists of liturgical celebrations. Neither mentions a feast celebrating the Nativity of Jesus.

Origen, the prolific theologian of the mid-200s, summarily dismissed the notion of such an observance on biblical grounds. Pointing to the birthday celebrations of Belshazzar, threatened with the writing on the wall (Daniel 5), and of Herod Antipas who beheaded St. John the Baptist (​Matthew 14:1-12; Mark 6:14-27; Luke 9:9), Origen concluded, in Scripture, only sinners celebrate their birthdays!

Nonetheless, despite the resistance of bishops and theologians, ordinary Christians wanted to celebrate Jesus’ birth — but on what day? It is not recorded in the New Testament.

The one clue, that shepherds were keeping watch by night over their flocks (Luke 2:8) does not really indicate spring or autumn as some commentators have theorized. Bethlehem is only six miles from Jerusalem and shepherds tended their flocks all year long due to the need of having lambs for the daily sacrifices of the Temple.

In 200, St. Clement of Alexandria, who supposed the Nativity to have occurred on November 18, speaks of Egyptian scholars suggesting it took place on May 20; others thought it was April 19 or 20. Clement also reports how the Basilidians, a heretical group, kept an observance on January 10.

Inside the Vatican magazine notes in an unsigned article, “The 25th of December, Pagan Feast or Patristic Tradition?”:

According to Pope Benedict XVI, the first person to clearly assign Christmas to its current feast day was St. Hippolytus of Rome. In his Commentary on Dan­iel, which was written c. AD 204, St. Hippolytus wrote: “For the first advent of our Lord in the flesh, when He was born in Bethlehem, was December 25th, a Wednesday, while Augustus was in his forty-second year, but from Adam, five thousand and five hundred years.” Writing roughly 150 years before any known records which designate December 25th as Natalis [Sol] Invicti, Hippolytus gives no mention of the Roman feast. It would seem the Christian use of the date was quite independent from all pagan solemnities. Where then did he get this date?

Tertullian a contemporary of Hippolytus, supplies the answer. Comparing the Jewish lunar calendar to the Roman solar calendar, Tertullian stated that Christ suffered:

… under Tiberius Caesar, in the consulate of Rubellius Geminus and Fufius Geminus, in the month of March, at the time of the Passover, on the eighth day before the calends of April, on the first day of unleavened bread, on which they slew the lamb at even, just as had been enjoined by Moses.

By Roman computation, the eighth day before the calends of April was, as we count time, March 25th.  Tertullian followed the Jewish belief that prophets lived “integral lives,” dying on the same calendar day on which they were born or had been conceived. 

Two centuries later St. Augustine, taking up the question of uniting Christ’s conception with His death, concurred with Tertullian:

For He is believed to have been conceived on the 25th of March, upon which day also He suffered; so the womb of the Virgin, in which he was conceived, where no other mortal was begotten, corresponds to the new grave in which He was buried, wherein was never man laid, neither before Him nor since.

This principle led another contemporary of Tertullian also living in Rome in 221, the Christian historian Sextus Julius Africanus, to identify the date of Jesus’ conception as March 25th, the same date on which he held the world to have been created. Nine months later, December 25th, would naturally be observed as the date of Christ’s birth.

The Holy Family at the Nativity is depicted in this painting by artist Laura James. The feast of the Nativity of Christ, a holy day of obligation, is celebrated Dec. 25. (CNS/Bridgeman Images)The Holy Family at the Nativity is depicted in this painting by artist Laura James. The feast of the Nativity of Christ, a holy day of obligation, is celebrated Dec. 25. (CNS/Bridgeman Images)
The Holy Family at the Nativity is depicted in this painting by artist Laura James. The feast of the Nativity of Christ, a holy day of obligation, is celebrated Dec. 25. (CNS/Bridgeman Images)


In this, Africanus followed the same line of scriptural reasoning as St. Polycarp (c.69-c.155), bishop of Smyrna and disciple of St. John the Apostle, who concluded that Christ's birth most likely occurred on a Wednesday, because Sol (the Roman name of the sun) was created on the fourth day, an event foreshadowing the appearance of Jesus, the Light of the world. Polycarp found it fitting that Christ, the prophesied “sun of righteousness” (Malachy 4:2), should be born on this day. “Did not the sun disappear, hiding in shame, at His death”?

Still, Tertullian had to make clear that Sol was not the Christian God. St. Augustine also denounced identification of Jesus with Sol as heresy, urging Christians not to celebrate the sun, but Him who created the sun. In like manner, Pope St. Leo the Great (440-461) rebuked the persistently pestilential belief that the birth of the new sun, as it was called, was being solemnized as the Nativity of Christ.

It has since been proven that it is impossible for March 25th to correspond to the 14th Nisan, the preparation day for Passover in the Jewish calendar, the day on which Christ died. The only date which matches all the data of the Gospels and Acts of the Apostles is Friday, April 3, AD 33.

The first notation of a liturgical celebration of the Nativity of Jesus is given as being celebrated in the year 336. The Mass was conducted on December 25 in Rome by Pope St. Julius I.

The Catholic Encyclopedia discloses the earliest evidence of the Nativity being an annual memorial appears in the Philocalian Calendar, compiled in 354. The same source states, “In the ‘Depositio Martyrum’ a list of Roman or early and universally venerated martyrs, under 25 December is found “VIII kal. ian. natus Christus in Betleem Iudeæ” ([On the] 8th day of the kalends of January: the birth of Christ in Bethlehem of Judaea).

In the Eastern Church, the calculation of the Annunciation was April 6, so the Nativity was celebrated on January 6. Eventually the East accepted the December 25th date for celebrating Christ’s birth, with January 6 commemorating the visit of the Magi and their veneration of the Christ Child.

Pope Siricius, writing in 385, distinguishes the feasts of the Nativity and the Apparition, later known as Epiphany. The Second Council of Tours, in 566 or 567, proclaimed the duty of fasting during Advent and the sanctity of the “twelve days” from Christmas to Epiphany.

All the calculations from Scripture demonstrate that the search for the true date of Christmas, the name taken from the late Old English Cristes Maesse first found in 1038, was begun in a serious search for truth. A widespread but mistaken belief holds that Christmas derives from the pagan Saturnalia debaucheries and “the Birth of the Unconquered Sun” festivities. Such arguments, as my attorney friend Dennis Ashby in Des Moines says, amount to nothing more than, “Monumental bickering over the utterly inconsequential.”

Did early bishops, unable to stop the celebration of pagan midwinter frivolities, simply “baptize” them? Britannica begs to differ: “One of the difficulties with this view is that it suggests a nonchalant willingness on the part of the Christian Church to appropriate a pagan festival when the early Church was so intent on distinguishing itself categorically from pagan beliefs and practices” (from the article: “Christmas”). 

Seeking a device to unify the various pagan cults of the Roman Empire the Emperor Aurelian (270-275) instituted the festival of the sun on December 25, 274. It was almost certainly an attempt to create an alternative to commemoration of the birth of Christ already being observed on that date.

The myth of the “pagan origins of Christmas” is therefore without historical substance. As G. K. Chesterton wrote, “Anyone thinking of the Holy Child as born in December would mean by it exactly what we mean by it: that Christ is not merely a summer sun of the prosperous but a winter fire for the unfortunate.”


Sean M. Wright, an Emmy-nominated television writer, is a Master Catechist for the archdiocese of Los Angeles. He is a member of his parish’s RCIA tam and replies to comments sent him at [email protected]

“Quando Christus natus erat de Beatissima Maria Virgine?” asked several Christian historians and theologians living in the Roman Empire during the first 300 years of the Christian era. Over the centuries many Christians still ask: “When was Christ born of the Most Blessed Virgin Mary?”

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