The four major world religions, measured by the number of adherents, are Christianity, Islam, Hinduism, and Buddhism. Other religions with substantial numbers of believers include Judaism, Sikhism, and Jainism. Some points these religions have in common include the following:
1. Religions have a creed, a statement of belief which makes it possible to convert to the religion. Christianity and Islam, which actively seek converts, have the simplest creeds. Muslims, for instance, believe that "there is no God but God, and Muhammad is his prophet." Although religions which do not proselytize tend to have more complex sets of beliefs, there is still a collection of propositions about the world, the acceptance of which makes you a Buddhist or a Hindu.
2. Religions form communities that gather together in specific buildings designed for the purpose of worship. Churches, mosques, and temples all tend to be striking constructions which are clearly central to the communities in which they are built.
3. There is generally a specific ritual of form of worship which is followed when adherents meet, though in some sects, this may be very informal.
4. Religions perform several functions, one of the most important of which is to answer questions. These include questions about the nature of the world (How did the universe come into being? What will happen to me after I die?) as well as moral questions (In such a situation, what ought I to do, and why?).