As a non-practicer of any particular religion, I've observed that there seems to be harsh feelings between some Christians and some Catholics.
Christians don't seem to respect the rituals of the Catholic Church - after all, going to mass doesn't mean you're a good person, especially if you turn around and sleep with someone who's not your spouse.
Catholics consider themselves Christians too and don't understand why some people disinguish themselves as Christians - after all, both religions are about learnin the lessons of God's son Jesus.....
I say that everyone should learn to respect that the other person may have different beliefs (or non-beliefs), as long as they are not harming society. Practicing religion does not make one better or worse than anyone else.
If one were to study the history of religions, many are just branches of the same tree.