Well I'm glad she's not a zombie. You might think she's into you and really she just wants to eat your brain.
Buddy it's starting to sound like this is more about too many girls you're interested in then your religion separating you from the one girl you really want to be with. But if you want to be with this girl maybe this will help...
Problem: Her Christian faith and your agnostic-atheist faith are incompatible world views so instead of being as close as you might like to be, your just friends who tolerate each others religious world views.
Solution:
A. The easiest thing is, get her to believe what you believe. Tell her the things you didn't like about your former faith and how you became convinced it's a lie and there is no God. If you convince her, then you can let her know that without a God you can become your own moral authority without worrying about death. She becomes her own god to do whatever she thinks and feels is right. If she feels like she wants to be with you then you both can be closer.
Possible Scenario: She becomes your girl and you live happily until. She really thinks about her new faith. After awhile she lets you have the other girl too. Later, she wants to be with both of you. But she finds she's really just into the other girl, but it's okay she wants you to be their baby-daddy with no strings attached. No reason why not? After awhile though maybe the baby bump becomes unfashionable for her figure or economic status. She decides pregnancy isn't for her so she will change a few terms around. Now she says "fetus bump" and chooses "abortion" instead of killing a baby. But as a friend you or her girlfriend will probably be there to help her deal with the psychological stress a majority of women deal with after... "the procedure". And then you can do it again if you want or she can swear off human relationships and marry an animal. Maybe the whole experience puts you off girls and you're off the hook, besides maybe you were curious one time? But maybe she goes to term and you get together, besides the economy's on the uptick so you keep... "it" and there's hope for a future talent like the next John Petrucci.
B. Believe what she believes. You can ask her to share what she believes with you. But I'm going to go out on a limb and assume I understand her Christian beliefs and maybe help answer some of your religious questions. She more than likely believes that everyone has sinned and falls short of God's glory. And that everyone whose honest, will admit they've broken at least one of the 10 Commandments. She probably believes that. How about you? You seem honest, sincere and reasonable so you could ask yourself if you've kept pure. I know I've lied, stolen, used God's name as a cus word and Jesus said, 'lusting for a woman in the heart is adultery'...etc. It's like breaking the law and you're going before a Judge. Pay the penalty for sin or be locked up in hell. It's appointed once to live and then the judgment for our lives by a just God. So no matter how much of a nice guy I am or what church I go to or how much I feel sorry and or my religion changes my ways, I deserve justice and am unable to pay my fine. But God, whose, rich in mercy and loves this world sent His son Jesus to pay the price for you, me, her and the whole world. The Son of God, went willingly to the cross, not condemning the world that deserves condemnation, but dying for it. He proved "It is finished" by paying for us in full. He gave us hope by dying and raising from the grave for proof of eternal life. He's not on the cross anymore. Today, most Americans are celebrating this event. Because now there's time and you and I can change the way we think or "repent" and turn from living in sin and trust in the only One who gave His life as a gift, the only one who could pay the price for the worlds sin, your sin, my sin, her sin. He died because we sinned and why would He pay such a price if He didn't see how valuable you are. You're loved by God. "Greater love has no one than this, that one lay down his life for his friends." It's God's goodness that leads us to change the way we think/repent so friends learn what friends like and do it because it's good for the relationship, not to create religious zombies.
This is probably what she believes. Really though if this makes sense girls are the least of you concern if you don't settle your eternity before you die and you don't know when that will be. This isn't to scare you into something you don't believe, but you asked about religion earlier. I believe God doesn't want to enhance your life by getting you a Christian girl. He wants to change your life to make you a son. But she might be able to point you to help if you decide on option b which is really the only plan A any of us have. If this resonates with you, if it makes sense, think on it read the bible for yourself, and ask God to take you where and who you need to fellowship with, that's not the internet.