"Evil" itself is of course a concept born out of religion, Ron, implying the involvement of some supernatural, Satanic force.

If this latest horror was committed, as you seem to assume, by people whose thinking was firmly grounded in the here and now, then it would indeed be one small step (there have been others) towards rebutting my suspicion that many of the worst things that happen are done by people inspired by superstitious/religious beliefs, or result from the exploition of such beliefs.

I strongly suspect, however, that the perps in this case had some crazy notion that they were fulfilling their god's purpose. Their post-crime behaviour had all the hallmarks of a pitch at martyrdom, in the belief that they were soon be rewarded by their maker.

So yep, broadly speaking, I'd say irrational behaviour and religious beliefs sit comfortably together, and likely did so in the present case. But that's not to say you can't have one without the other, nor that all people of religion do crazy things.