I'll revisit this later but the immediate thing that comes to my mind about this subject:
I believe the reason "religion" (more specifically "Christians") are attacked quite a bit by metal bands (mostly of the death/black genre) is because of a scewed and uneducated definition of what a "Christian" is.
You bet religion/Christians are an easy target, especially if your definition of them is defined by the finger pointing, hypocritical, holier than thou, headline making preachers and churches. The sad news is, they in no way define who and what a true Christian is supposed to be. They make me sick to no end with their views because they aren't Bible based, quite the opposite. Period. Sadly, that's who end up representing "religion" and "Christians" as a whole. So in my opinion, when bands do this (attack religion, etc.), they are no better than the subjects they are attacking. It's a whole big hypocritical stew, yummy.