All warfaring nations have committed atrocities, I'm not denying that and I'd be the first to condemn these actions if they'd be discussed now. What I'm unconvinced of is whether Americans would put their own personal survival lower than the prospect of martyrdom, as long as they don't get indoctrinated by religious beliefs of this sort. It's a similar argument of whether the Nazis or the Khmer Rouge were just a product of their circumstances - no, I don't think so. Their ideology was actively warped to a point where it was detrimental to human survival, detrimental to what our biology tells us to do, and something everyone with a clear mind is IMO obligated to stand up against.
There's a difference between terrorism with clear political goals and terrorism that's targeted at our very way of life. One can be attributed to circumstances and can be dealt with in a more or less peaceful matters (e.g. 'give them what they want'), the other cannot.