Officially anyone who declares that "There is one God and Muhammed is his prophet" is a Muslim. But many Muslims argue that the beliefs of the Ahmadi community mean they cannot be part of the faith. There are about 12 million Ahmadi worldwide and their headquarters, originally in Pakistan, are now in London. Their founder, Mirza Ghulam Ahmad, claimed to be a prophet, although a lesser one than Mohammed, and it is this claim that critics say put his followers outside the fold of Islam.