It was the disbelievers who kept you from the Sacred Mosque and prevented your sacrificial offering from reaching its proper place. God would not have kept you from fighting the disbelievers, had there not been believing men and women (among them) whom you did not know and whom you might have unknowingly harmed. God did this because He grants mercy to whomever He wants. Had they been distinguishable from the believers, We would certainly have punished them with a painful torment.