RE is the easiest subject to pass. Its not even about religions mostly, but more about morality. You can make most of it up. I didn't revise it at all (Didn't even glance at anything), and i got a B.

Rule to remember: If you have to go against anything, say the Catholics are against it. Cause 9 times out of 10, they are. e.g. Abortion, Sex before Marriage, Divorce, Cohabitation, remarriage etc etc. Say that everytime, and you'll pass it no problem