You can't call what they do to their youth over there nothing short of brainwashing.All they do in the radical islamic schools is rock back and forth,sitting on a hard floor and recite the Koran for hours on end.No wonder they're easily swayed into strapping on suicide vest.
The inner/secret contents of one's "heart" are only truly discernable by one Being in this universe.
That being said, I wouldn't entrust the eternal destination of anybodys eternal soul on speculations concerning "general revelation" and "age of accountability".
I guess it boils down to this: a mother and child get on a bus, and mother hands her two year old a live-grenade to play with. Child pulls the pin and twenty five are killed, and thirty are wounded (10 being lamed for the rest of their lives). Who goes to hell?
My position: the two-year old, e.g., if they haven't achieved the age of accountability are instantly with the Lord. With respect to anybody else's fate, I couldn't unequivocally state anything except what is proclaimed in Jn 3:16.