Christian dad broke us up

[Alex K]

That she doesn't know, and that a lot of couples manage this. She's not really Christian her self becUse she hates religions but somehow bipolar about being agnostic/Christian

That is very important information. So she would basically have been ok with a milque toasty christian upbringing of potential children with a bit of atheist influence from your side.
(And if she would tell her parents that, they will probably hate you even more because they'll think that it was your evil influence. Damn.)

I must say though one can't blame her too much, it is a very difficult situation at a relatively young age, to basically be threatened to be cut off by your family. It really is their fault. Who knows how other otherwise happy couples would hold up under such pressure...