OP, take it from me. I've dated a decent amount of women and many of them were Christians.
It never works out in the end when you're an athiest. You're not going to change HER mind and she likely isn't going to change your's. But she has dedicated her entire life to God. Every little thing will be a blessing from God, from every meal to every bright sunny day, to just waking up in the morning. It would get on your nerves.
I've met women who are so deep in Christ that they may as well be nuns and I don't mean to say they're just major Jesus freaks. They're people who sew Jesus into their very fabrics.
And you want to date a woman who is not only a Christian of the most unbroken faith, but she is someone who has sacrificed everything for that faith. She has chosen to never have a romance with anyone but Christ, will never have children, can never even live anywhere outside of the church structure.
So if this is real, which I suspect it isn't, you're really naive for thinking you can be with her.
TL;DR version: you know how waitresses, strippers and prostitutes pretend to like you for money? That's what this nun is doing to get you to God's side. She'll never date you because she's got a super tall, buff boyfriend back home who takes all her money.
Mmkay, sugar?