What the hell is wrong with these people?
Welcome to the Sadriyah market, north-central Baghdad. Other than the blackened vehicles and smoke, this slightly resembles some areas of, say, Meknes. But it's not.
Two ideas regarding motivation, not necessarily exclusive:
1) However the partisans organize themselves, they agree that increasing violence will drive off the invaders, er, "protectors". So this is essentially atheistic terrorism.
2) Given 1), many angry sorts have available cover for genuinely religious terrorism. Not that any of this crap, whether in Baghdad, Algiers, or Louisville, is remotely allowed by the Qu'ran.
(Dear US: Get the fuck out. What do you think you're doing?)