Extraordinary evil. Imagine the religious imperative behind the chanting of "Allah is greatest" while gang raping a girl. (vid hat tip Jack)
UPDATE: Robert Spencer translates:
They're shouting "Nasara! Nasara! Nasara!" (Christians! Christians! Christians!) as they set upon the terrified woman. And then "Allahu akbar" (Allah is greatest) and "There is no god but Allah."
But remember: it is "hate" to oppose this savagery.