What's with this attitude that unless you're a Christian, just having your beliefs should be enough?

Hell they do it to other Christians! I am Catholic and have been preached to many times about how I am not going to Heaven because I am not a true Christian, excuse me? I look at it this way, my faith, my business, your faith, or lack of faith your business. I have actually found that the Atheists, and other non-Christians act more like a true Christian should act.