There are plenty of good Catholic Democrats. Kerry and the Kennedies just to name a few prominent ones.

A good American Catholic recognizes that the Catholic church's beliefs can be a guide for their own behavior... but that our national belief in religious freedom means that you can't impose Catholic dogma onto the general population through law. That's why those Catholic Democrats are in favor of letting people have the freedom to make their own religious and moral choices.

Besides, Republican Catholics don't do such a good job following the pontiff's lead: the Pope opposed the Iraq invasion and doesn't approve of capital punishment.
Kerry a good catholic? What a joke. He just used catholicism to try to get the popular catholic joke.

Part of being a Catholic is trying to spread the word of God. This is kind of hard if you allowing such practices of abortion and gay marriage happen at the same time. You aren't really doing your part.

Being a Republican does not mean you always have to be pro war and love to kill things. It just means u have more conservative views on the rest. For example, you could love owning a gun for target practice, but be completely against hunting. It is also means that you could be a Republican and not completely agree with the war. Just because one Republican wants war, does not mean everyone else does.