OK, I tend to stay out of the Islam/ Middle-Eastern politics threads, because no one ever listens and they all turn into flame wars. Hopefully, this one will be better.
Anyway, I don't conflate "radical Islam" with Islam as a whole, but that's not to say it doesn't worry me.
One thing I've observed on this forum is that many of our Muslim members seem to be more concerned with defending the faith than denouncing those who pervert it. A common tactic is "they're not really Muslim." To outsiders, this comes off as hiding your heads in the sand, and THAT worries me, too. If the Islamic community won't rid itself of these rabid murderers, what are their targets (Westerners) to do? We CAN'T reform, only attack.
As for your comparison... Christian proselytizers may be significantly more numerous (and annoying), but they're not out killing thousands of people. Still, I laughed.