How do you explain in a very simple, easy to understand way to someone who is not at all educated in Catholicism how we arrived at the date of December 25th for Christmas? I have someone hitting me with “December 25th is not in the Bible and that Jesus was probably born in the summer.”
As we do not know the exact date of Christ’s actual birth, feel free to tell your friend that the date of December 25 for Christmas was arbitrary. The Church could have decided to choose another date on which to celebrate the birth of Christ, but thought December 25 perfect for a variety of reasons. Perhaps the easiest to understand and the most scriptural is that December 25 is close to the winter solstice. After that date the days start to become longer, thus it is at the beginning of a season of light entering the world (cf. John 1:5). The summer solstice (after which the days start to get shorter), on the other hand, falls near June 24, on which the Church celebrates the birth of John the Baptist, who declared of Christ, “He must increase, but I must decrease” (John 3:30).