The quest to know the day on which Jesus was born is no new thing. The early Christians have sought to know it too. Around AD 200, Clement of Alexandria wrote:
“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 28th year of Augustus, and in the 25th day of [the Egyptian month] Pachon [May 20] … Further, others say that He was born on the 24th or 25th of Pharmuthi [April 20 or 21]”.
Certainly, Jesus was born on a certain day. Which day? The actual birthday of Jesus Christ is not given by the Bible and it is not known. The birthday of Jesus can be any day; it can be one of the proposed dates such as 25th December, 20th April, 21st April, etc. or it can be any other date.
However, we celebrate 25th December as the birthday of Jesus due to a smart analysis of the early Christians. According to a Roman historian Sextus Julius Africanus (AD 160 – AD 240) who lived in the second century, Jesus of Nazareth was conceived on 25th March and, since pregnancy lasts for nine months, was born on 25th December.
The explanation behind this conclusion takes us to Luke 1:1-20, where Zachariah was doing his priestly service at the temple on a festive day, burning incense, while the whole multitude of worshipers were praying outside at the hour of incense. Then an angel of the Lord appeared to him to announce the conception of his son John the Baptist.
The early Christians held that this festive day in question is Yom Kippur, a holy Jewish festival held in October. John the Baptist was conceived by Elizabeth from the time the angel visited. And since John the Baptist was six months older than Jesus, the conception of Jesus happened in March of the following year. Conceived in Match, Jesus would be born nine months later in December.
The date 25th December was acknowledged by Christians as the proposed birthday of Jesus as early as the 2nd century. It can be deduced that Roman Christians had started observing Christmas on 25th December; it might have started on a small scale; until it was widely accepted by the Christendom.