The word ‘Christmas’ comes from an old English word meaning ‘Mass of Christ’, and dates back from the beginning of the first millennium. Christians celebrate on that day the incarnation of the Son of God, as the man Jesus of Nazareth and the beginning of the new era of Grace.

Based on all traditions, most Christians have always celebrated this date, since the 4th century, on the 25th of December of the old Roman Calendar, called Julian Calendar, in forced in the whole Roman empire at the time. However, since the creation of the Gregorian Calendar by Roman Pope Gregory XIII in the middle ages, this old 25th of December became the 7th of January in the new updated Gregorian Calendar, and the new 25th of December as we know it today came into existence.  However, many eastern Christians still keep the old 25th of December on the 7th of January as it shows in the Gregorian almanac, and some other minorities like the Armenian Christians continue the even older tradition of commemorating the nativity of Jesus together with his baptism on the old 6 of January.


The Bible does not command to celebrate any festival indeed. Christians are totally free of commandments about ‘sacred days’ and holidays. But after Easter, the nativity of our Lord became to be considered the second most important celebration in the life of our Lord, and the common consensus of the living Church around the world decided to commemorate this event.

Even though the first Christians like Irenaeus, Tertullian and Origen do not mention the nativity as a celebration (1), this started to be accepted by the beginning of the 4th century, until the first official celebration took place in Rome in the year 336 CE (2).

However, this came as a development. Already Clement of Alexandria claimed that by the middle of the year 200, Egyptian theologians started to decipher the exact date of the birth of our Lord, and some came with different dates, from the 28th of March, to the 20th of May (3). But there was never a universal agreement.


Since the early second century, together with the celebration of the crucifixion of Lord Jesus (Easter), the celebration of his baptism by John started to be celebrated as the initiation of his public life, and therefore, also his nativity as human, on the day of the Epiphany, on the 6th of January. And this was the proto-Christmas celebration in most places around the Roman Empire, well before Constantine (4).

By the beginning of the third century, Hippolytus of Rome, proposed his idea that Jesus may have been born on the 25th of December (7th of January in the old Roman calendar), since it was nine months after the beginning of Summer, which fell on the 25th of March, as it should correspond to the ‘Sun of Righteousness’ (Malachi 4:2) that was Jesus (5).

It was finally in the 5th century, with John Chrysostom that this idea became the official version in Christendom. He said that the birth of Jesus occurred on the 25th of December, nine months after the annunciation, which occurred six months after the conception of John the Baptist, which occurred when his father Zechariah had an angelic encounter when he was officiating in Yom Kippur, on the 25th of September of the year he lived (6).


While this idea progressed purely on religious grounds, it was also impulse by a political- religious wave.

Pagan Rome celebrated since the days of Emperor Aurelian in 274, the day of the ‘Sol Invictus’, or the ‘Invincible Sun’. It is said that with the intention of overtaking this pagan custom from the Italians, made the bishops of the time, to adopt the same date to celebrate the birth of Jesus, the ‘Sun of Righteousness’ (7), however, others think that Emperor Aurelian chose the date of the 25th of December to overtake an already existing Christian celebration (8).


1 - About the 25th of December been chosen to suppress the pagan roman Sun festival, it is ambiguous. If we consider the early third century eastern preoccupation with identifying the date of the birth of Jesus, it is quite possible that Emperor Aurelian could have tried to paganize the date, already considered, but not stablished by Christians as we have seen. But it also could be that the Christians tried to ‘Christianize’ a pagan festival, replacing Jesus instead of the Sun. None of these theories can be proven beyond doubt, but are used today by certain groups that without basis sustain the later possibility with the intention to discredit Christmas of any real Christian content. It must be kept in mind, that even if the second theory could be right, the celebration is purely about the incarnation of Jesus, based on biblical events, regardless of any pagan context, therefore it is not sinful at all.

2 - The date of the celebration as calculated by Clement of Alexandria and Chrysostom, as the 25th of December, based on the conception of John the Baptist, which in turn is based on the date of the office of Zachariah in the Temple during Yom Kippur, is based on assumption.

Zachariah belonged to the eighth group of temple priests of the division of Abijah (Luke 1:5), who officiated over a 24 week roster, for a week, which it would give them two participations per year, on a changeable date every time.

The Gospels do not specify which date was Zachariah officiating on. It could have been in the Day of Atonement or at any other time, specially since it is hard to identify the year that event took place.

3 – Considering the biblical narrative that tells us that the shepherds were out with their sheep during the night (Luke 2:8), it unlikely that this could have happen in December, since that month is really January, according to calendar of the time, and that is the coldest part of winter, with snow, which extends from November to April. But not only this. The census that determined that our Lord may have been born during the trip, could not have been called during the winter months in Judea.


The most credible possibility is that Jesus could have been born from late March (Spring), to early September (Summer).

Now, considering the possibility that Zechariah’s two weeks of temple duties fall around the middle and end of every year, we are left with April to June, and then from October to November in modern times, which will give July to September, or January to February as the birth of Jesus.

Even though we cannot with certainty identify when exactly was Zechariah in the temple, it is clear that it may have been during his first rotation, not the second, which will place Jesus during the winter months.

Another thing to take into consideration is the weather between Summer and Spring.

It is unlikely that the Romans could subject their own soldiers and transporters to either extremely cold or hot temperatures and extreme rains (Luke 2:1). This narrows the possibility to the months where the weather is ideal, between the months of May to September with temperatures from 18 to 28 Celsius, and little rain.

The most probable time for the nativity of our Lord was 15 months after the first cycle of the Temple service of Zechariah, which will give Jesus’s birth from July to September, the most appropriate time of the year for the shepherds to be out all night, travel at night, and the census to be called in Judea.

But even this is only a simple hypothesis.

It is impossible through the limitations we have, to make a conclusion beyond doubt on the nativity of the Lord.

What is important is that all Christians agree on celebrate the incarnation of the Son of God, and that He came to die for our salvation. It is through this act of love, that we can have the hope of forgiveness and eternal life.

And that is what we are grateful and happy for.


Omar Flores.


(1) Origen, Against Celsus 8:22.

(2) The Chronography of 354, Part 12.

(3) Clement of Alexandria, 1:21.

(4) Geoffrey Wainwright, Westerfield Tucker, Karen Beth, The Oxford History of Christian Worship, 65.

(5)  Watson E. Mills, Edgar V. McKnight, Roger Aubrey Bullard, Mercer Dictionary of the Bible, 142.

(6) Oxford Dictionary of the Christian Church, ‘Christmas’.

(7) Ramsay MacMullen, Christianity and Paganism in the Fourth to Eighth Centuries, 155.

(8) William J. Tighe, "Calculating Christmas".