Why does religion make everything tense?

I've noticed that when asking questions about religion or spirituality on Youtube or simply anywhere, things can get tense. Why is that? Personally for me it feels like if I post a comment about a favorite band or video game then people on that same page might agree with me, or we would chat about it. But when it comes to religion there is so much prejudice and immdediate contempt towards the other person. This isn't really a question, it actually makes me really sad. So please share your opinions.