Regarding Tom & Dave's catholicism - I listened to a great interview with Tom on a local radio a year or two ago.
He pretty much said that the 4 guys you see on stage are merely cartoon characters of the real men themselves. As he said once they are off the stage they are just normal men, some with families and so forth. Tom came across as a very nice, polite and friendly person. Basically he stated his time as a triage nurse (or hospital orderly I think it was) inspired a lot of his song writing. He writes mostly about the horror and war themes whilst Dave, Kerry wrote mostly about the religious, satanic stuff.
But at the end of the day it isn't his mantra - it's simply lyrics - well from Tom's point of view. I have read that Kerry is pretty much what you see is what you get on and off stage.
So in reality the perception that life imitates art is still blurring the lines.