"I will have no family at all if I do this."

Well, basically. But when shit hits the fan those folks won't help you anyway, and those who would disagree with you, yet would still stay (for whatever reasons -- they too don't want to remain alone), would stay either way.

I said what I said because I went that route few decades ago. It wasn't about atheism and Christianity, but hypocrisy and bigotry in general, and I was left with exactly one family member (out of dozens), whose self-interest I can rely on (sadly, neither that person is a "friend" by any means). And I would not have it any other way. But of course, your mileage may vary.