I'm sure they believe everything on Ancient Aliens too

I did do my own research and all kinds of Christian websites popped up proclaiming that those holidays have Pagan origins, (why Halloween? It doesn't have anything to do with religion).

Any site that claims that is not doing their own research and is parroting old misconceptions of protestants that tried to discredit the church for their own financial gain. If you don't know why Halloween exists and what it means, you obviously didn't do any real research either.

You know what? F**k it. I have better things to do than to look up the origins of holidays. Believe what you want, and so will I. Existence is too short to spend time on things like debating the origins of holidays on the internet.

https://www.catholic.com/qa/is-easter-an-english-translation-of-ishtar