I was in the same situation so I went to a religious hypnotist, bought Christian oriented books that addressed an atheist's doubt, and went to Church, all while praying twice (or more) a day that God will come to me. It worked. I was an ardent Atheist since childhood and now I'm a total Believer who goes to Church at least twice a week. I have a great marriage to a very religious Catholic and have converted to the faith myself. I hardly remember my old self as an Atheist.
If you find a great religious hypnotist it will do wonders for your spiritual self. God bless you and your girlfriend.