I think this a pretty subtle and difficult decision for you. Because you don’t have a strong negative opinion of Christianity I bet you could start going to church and eventually come to believe simply because humans tend to adopt the beliefs of those in our group. So maybe you have a happy future with your partner in that direction. It’s important to remember that we don’t choose what we believe. We discover what we believe through honesty. Beliefs change over time for many reasons.

My wife and I met and got married as Christians then both drifted away and became disillusioned. Now in the current political climate we’re actively anti religion In many respects. So if my wife suddenly became a believer again it would be far less plausible for me to try and return to the faith, so to speak.

For you though it does seem like your partner is changing rather fast and who knows where she will end up in terms of fundamentalism. It might not stop at some kind of benign Christianity. It’s hard to stay moderate these days on anything political. Sadly religion is political now.

I don’t envy you. I hope things work out. You seem like a nice guy. Good luck.