Seriously, there isn't.
That's because Christmas has never really been about Christ. It started as a minor holiday. For early Christians, the big deal was Christ's resurrection, not his birth. The birthday was no more important than any random Saints days on the calendar. It was celebrated around the time of the Winter Solstice for a number of reasons, none of them having to do with anyone thinking this was the actual birthday of Jesus. It was mostly about the Winter Solstice and people celebrating that already so it made a convenient for Christians to have a holiday they could celebrate around that time too.