Two questions:

When did you decide you no longer believed in God? (The way you have phrased your opening statement, you seem to have believed in God at one point or another.) This doesn't have a lot to do with any discussion, but it's a point of curiosity. I've never believed in God, so I'm always interested in the transition between states, from believer to non-believer, or vice-versa.

Second, what is his professed faith? Does he attend church, etc? Or is he a casual believer?

In my experience, fundamentalists have given Christianity a bad name. (Fundamentalist Muslims are doing the same thing for Islam, near as I can tell.) So, I have noticed several Christian acquaintences distancing themselves from Christianity. This generally calls into question their devotion to their faith, as it seems the whole "giving yourself to Christ" is an intrinsic part of belief.

The best resolution to your question would be to ask him outright, "If you believe that Christ is your personal Savior, why do you question your Christianity?"

Otherwise, you'll only get a bunch of speculation from the likes of me, who have no way of really knowing what's on his mind.

Massive, torturous amounts of croco-duck cognitive dissonance.

I'm not sure when/why I made that final transition, actually. I think it helped that my parents were never strongly religious. I was baptized Lutheran but I don't even really know what the distinguishing features of Lutheranism are, so that shows you how much they emphasized my religious upbringing. My parents took me to Sunday School as a young child. I remember coloring pictures of Noah's ark but I don't remember anything particularly traumatic or enlightening about church. I think it was sort of a non-issue and we just went to look good. My father had a thing about looking good to the community and going to church was just what "proper" citizens did. I don't remember either parent being particularly religious, although my mother was  more "spiritual", not belonging to a particular church so much but having lots of books about "conversations with God" or something, and talking to me about God from time to time.

I think the transition began as a slight nudge in high school. I took a class in Greek and Roman mythology. When I asked the teacher why stories of the Greek gods were considered fiction and stories of the Christian god were considered fact he got indignant and refused to answer. He just replied that stories of the Christian god were true, and that was that, as if that settled it. At that point I began to suspect there was no more reason to believe in one god over the other.

But, I didn't declare myself atheist or even agnostic at that point. In high school there were a lot more important concerns, such as whether or not I was wearing the socially acceptable brand name shoes. I pretty much just went about my business, figuring I believed in God but never really giving it much thought or attention.

I think the Bush adminstration and the "Rise of the Fundies" had a lot to do with it by snapping me out of my indifference. With this administration I realized that religion was no longer a non-issue with anyone. I've also always had an interest in natural sciences and I think that's played a part. In addition to having taken lots of science classes in college, I still enjoy watching the Discovery Channel, National Geographic, The History Channel and such, and the more I've learned about politics, history, science, human psychology, and religion, the dumber and dumber religion has seemed. At some point I just decided I was not part of that idiot crowd and now I'm thoroughly convinced that it's all nonsense.

http://www.rationalresponders.com/forum/13387

You should read that thread. I've experinced this a lot-xtians who deny having a religion. I think they think saying that will endear us to them.or something. Really it  just makes them look like they don't know what they're on about.