A Jehova's Witness in RCIA asked me about Christmas - here is what I said

Why do we celebrate Christmas on December 25th?

Pope Julius is widely believed to have been the Pontiff who set the date of Christ’s birthday as December 25th around the year 350 A.D. However, proof that the early Catholics celebrated December 25th as the date of Our Lord’s birth can be traced to the writings of Hippolytus of Rome. In his commentary of the Book of Daniel, dated to around 200 A.D., this early saint states that the birth date of Jesus is December 25th.

Why is this important? People will make claims that this date was done in response to pagan holidays. However, the historical record undermines these claims. For instance, the pagan holiday of Sol Invictus - the Invincible Sun – was also celebrated on that day. However, that holiday was not declared until the year 274 AD by the Emperor Aurelian. This makes it more likely the emperor borrowed from the Christians to secure power for pagan practices. Furthermore, the claim that Pope Julius chose December 25th to accommodate the pagan holiday of Saturnalia is also suspect as the earliest writings indicate that the two celebrations were not linked until modern times.

All this is important; however, it does not explain why the early Christians celebrated December 25th as the birthday of Our Lord. How did they arrive at this date?

In St. Luke’s Gospel, the Apostle gives us records of the birth of Jesus Christ and of St. John the Baptist. During the recounting of the Annunciation, we hear the Angel speak of the pregnancy of Elizabeth and describe it as being in “the sixth month with her who was called barren” (St. Luke 1:36). This means Elizabeth conceived her child six months earlier than the Annunciation and the conception was revealed to her husband, Zachariah.

Who was Zachariah?

Zachariah is described by Luke as a priest of the line of Abijah. His wife, Elizabeth, was also of a priestly family (Aaron) and a relative of Mary, the mother of Jesus. In St. Luke’s Gospel (1:8-9), we hear that he was ‘on duty’ in the Temple when he had his vision. The Ancient Christians believed he was a High Priest and was on duty for Yom Kippur, the Day of Atonement – which mostly comes in late September. The early Christians, therefore, simply did the math.

September -----------------------------------------June---------------------------------------------------December

Conception John the Baptist                   Birth of John the Baptist                                        Birth of Jesus

This still does not explain why the specific date of December 25th was chosen. There are two reasons: Christians of the 2nd Century had been significantly removed from the ancient Jewish practices and incorrectly believed that Yom Kippur was always celebrated on September 24th or 25th. Therefore, we celebrate the birthday of St. John the Baptist on June 24th, and the birth of Our Savior six months later.

Secondly, the Ancients believed that the longest day of the year was always June 24th. All the days following June 24th are days where the light begins to decrease until winter. The believe that December 25th was always the shortest day of the year, thus the beginning of a time when light begins to increase, would correspond to the Biblical statement of John the Baptist. “He must increase, but I must decrease” (John 3:30).

Of course, we do not know the exact date of the birth of Jesus; however, we can trust the Church because our earliest members shared a memory of what happened that was far closer to the actual events.

Is it allowed, then, for a Christian to celebrate the birth of Jesus Christ on December 25th?

ABSOLUTELY – and we need to celebrate it with great JOY!