It sounds like You can be independent? If so, drop an ultimatum. Could be like "Is girlie, non-christian me any welcome at this home?" question, yes or no? Drop responsibilities on them lol.

May feel shallow, but... like, none forces anyone to anything. If some pick their own paths, no need to push them to own believes - and that's for both sides?

Could You accept Your father being a pastor if he do accept Your way of being self (and maybe to not spread ugly lies, that religion priests do say all the time, as if Your dad do that too)? Could he accept accept You being Yourself (and attending xmass tree festive)? So, who's the bad one? (I believe I well know the answer).

That may be different per region - I'm living in some commonly religious place too, but many managed, to drop christianity from xmass tree festive, still family meetings happen, still giving gifts to close ones, still having spiky shinny tree at home still cooking extras, having day off from works and so on, but without any religious stuff (religious shit) in it. Some parts of xmass were stolen by capitalism, some are just liked and enjoyable.

Stay cute and safe.