Religion can be a sensitive topic, and if you talk with enough different people, it's almost inevitable that you will encounter a situation where someone takes offense even though you did your best to be fully respectful of their views.

Don't take it personally when this happens! In these situations, it is important to remember that you are not responsible for other people's reactions, and that just because someone reacts negatively does not necessarily mean that you've done something wrong.

Does this mean it's good to stop talking about religion (even with this particular person)? Not at all! I think it is important to challenge people. Just because someone gets upset in the moment doesn't mean that they are going to stay upset. My experience is that if you are consistently respectful to someone, and don't take it personally when they get upset, most people will quickly get past this feeling so that you'll be able to have a more constructive dialogue with them. You may even be helping them to work through some of their own issues.