How should I handle my adult daughter's behavior?

My 21 year old daughter lives in Chicago. My husband and I went to visit her over the weekend and while I was over there I saw in one of her drawers birth control pills. I know she has been seeing a man there for six months. I only met him briefly, however he seemed nice but to old for her (eight years older than her) I don't know what to do. I thought I had raised her better than this. I thought I raised her to be a good christian and mindful of the bible. I know she is an adult and can make her own decisions but I wish they weren't this. Should I talk to her about it? How should I broach the subject?