It does not take long in reading Jesus Mythicists before you encounter the claim that Jesus’ birth on December 25 is evidence that Jesus was based on other gods born that same day such as Osiris and Mithras. Is this accurate? There are a couple of problems.
One is that it is not really that easy to pin those pagan gods as being born on December 25. Usually this claim is based on a reference to the Winter Solstice (December 21), although it does not actually say they were actually born on that day.
The other big problem is that the Bible never suggests a date for the birth of Jesus. In fact, the early church seemed completely uninterested in the birth of Jesus as a celebration. We do not find any discussion of the date of Jesus’ birth is around 200 AD and even then, the suggestions are in the spring.
It is not until the fourth century that we find discussions of the birth being either December 25 (the West) or January 6 (the East). While it is possible that at that point they were trying to take over some existing festivals, the fact that many churches hold to a January 6 date suggests the Winter Solstice was not the key.
Whatever the reason that December 25 was chosen by some churches, its appearance in the fourth century tells us that this is irrelevant to the potential relationship of the Jesus of the Gospels to any pagan gods.
If you want to learn more about this, I recommend this post.
