Things that are widely considered historically true about a man called Jesus at the time
There was a man called Jesus who was a Galilean Jew with known activities confined to Galilee and Judea.
He was baptized by John the Baptist.
He called disciples.
He had a controversy at the Temple andwas crucified by the Romans near Jerusalem.
After his death his disciples continued.
Some of his disciples were persecuted.
No proof exits he was born in a barn, so no reason to get upset over such a thing.
Though it is an important part of 2 gospels out of 4 (and countless others unrecognised)
Lasty as the nativity is considered idolatry in strict christian reality only catholics should be showing it so that's 4 million people to offend in the UK, though if like me they are lapsed I expect most have better things to worry about