@abge, It sounds like your friend's problem is that she is confused and doubtful, which can be a very unpleasant situation to be in. To the extent you want to help her through that without being harsh or disrespectful of her beliefs, you could do it by making sure she has adequate resources from both points of view (her own and yours, that is).
It goes without saying that if you discuss it, you'll present your own beliefs and the reasons for them. To be maximally honorable, imho, you make her aware as well (or even make sure she has) the best resources on the other side. It's hard to say what those are without knowing her specific issues; MM recommended some. William Lane Craig is well regarded (though I have not read him myself). Ideally, she would have a better pastor/priest who could talk to somebody in doubt without making them feel awful about it. Such certainly exist, and you could help her find one.
I'm not saying you don't also present your point of view, obviously. I'm just saying -- recognize that doubt is an emotionally confusing and vulnerable time, as well as just intellectually confusing, so if you want to be careful that she makes a decision for the right reasons, and not just because you're a good friend, or she's afraid, or something, see to it that somebody on the Christian side is attempting to address her concerns, as well. Or that's what I'd say. (Not that you'll go to great effort, but you can make her aware that these resources exist and she should use them).
I read an autobiography once of Christopher Robin Milne -- the little boy in the Winnie the Pooh stories. His father, the writer, was an atheist, while he was a believer. His father wanted to deconvert him, and did so by sending him an atheist book and also a Christian book. He did end up deconverting (sadly, I'd say) -- and I must say, I don't think his father actually chose a very good Christian book. But I did think it was the decent way to go about it.