I had a similar conversation with one of my very religious Christian friends once. I don't think I offended him, but like you just had questions to ask regarding Christianity and his views etc.

Personally, the deeper wee got into the conversation, the more I really thought he had been brain washed into it. Its something he had no choice in as his family was religious, and not given the chance to make up his own mind, I don't think he could see it any other way. However that's just what I think.

I myself am not a religious person at all really, and I remember him telling me that although I was a good mate and a good person, because I wasn't Christian id be going to Hell.

Now I believe I stopped the conversation about there as there were things I new I wanted to argue back, but im sure they would offend him purely because of his beliefs.

Religion is such a tricky subject, and one hard to have conversation with because of so many conflicting views from so many people.