I don't think it'll do any good. It's imposible to ban a religion/cult. I'd say that, since Islam calls to conquer all the world, calls non-Muslim countries "The House of War" and aims to abolish democracy, anyone who proffess it should not be allowed to run in an election or to vote in it. Also the UN should not allow an Islamic country as a member since their policy is against its principles. Also a religious country is a discrimination against its minorities.
Some will say that Israel is a Jewish State, but Jews are an ethnical group besides a religion.