It is a country full of muslims so how can it not be muslim? Look into history, the caliphate was less united than people make out from the very beginning. evidence: the shia 2nd khalifa Umar(ra) was killed by a "muslim", uthman (RA) the 3rd khalifa was also killed by a "muslim", and by the time of the fourth caliph Ali(RA) the caliphate was virtually split into the commands of Ali(RA), Muawiya and Amr ibn el Aas. and guess who the fourth khalifa(RA) was killed by, yes you got it, by a "muslim". The leaders however of the KSA, subhanallah, can never reach the lowest level which is with the kharijies. Their "reward" is with Allah and so is the "reward" of the progeny of al-saud. Salam