The dating for the birth of Christ is based mainly on the death of Herod the Great. (March, 4 BC) The Scriptures state that the birth of Jesus was before and apparently not very long before, this event (Matthew 2). For this reason, Christ’s birth can be placed in the latter half of the previous year. The classical dating for Christ’s birth, which is celebrated as Christmas on December 25, was first used in the West in the 4th century with the eastern date being January 6. This is four years too late and was most likely borrowed from a pre-existing pagan festival.
There is no way to tell for sure what day or even what month Christ was born. We can, however, tell that December is unlikely due to the winter season being unsuitable for pasturing flocks. (Luke 2:8) A more reasonable date would be a couple of months earlier in mid to late September. This conclusion can be arrived at by comparing the date of Christ’s birth with John the Baptist’s.
It is told in Luke 1:5 that Zacharias was serving during “the course of Abia” when he was told his wife, Elizabeth, would give birth to John the Baptist. History tell that this period took place around mid to late June. If we add 9 months to this we can tell that John the Baptist was born around the end of March. In Luke 1:26, we are told that Mary conceived Jesus six months after Elizabeth, so if we add the six months to the date of John the Baptist’s birth we can conclude that Jesus was born sometime around September.