Can you help my friend with relationship problems?

My friend believes that it is not all about religion, it is about a one-on-one relationship with Jesus Christ, and i am with him on that. Recently he has started a relationship with a girl, who says that she doesn't believe in purgatory, working to get into heaven or a sinless Mary, but her father makes her go to a catholic church. The people at my friend's church have told him "do not be unequally yoked " -2Corinthians 6. He wants to believe that she has the same relationship with Jesus as he does, but he is scared that she will be decieved by the people of the Catholic Church. HELP?