Why do Mac users talk about Apple like it's a religion?

I like Apple. I think their products are great. I’ve always liked them. But why is it that so many Apple fans will talk as if Apple is a religion and should never be made fun of. Why do they get so angry when you disagree with something. Why do mac users have to be totally Anti-Microsoft as if they are the devil. I was like this for a short period of time but why are many other people like this forever. I have learned to respect other products and companies. Even though I like Apple more than Microsoft there is a point where this becomes a bit ridiculous. What causes people to be like this?