The world's many religions can be loosely grouped as nontheistic, deistic, polytheistic and monotheistic. Various schools of nontheistic religions, such as Buddhism, can be difficult to separate from philosophy, and many adherents regard these religions as strictly philosophical. Deism was popular among intellectuals during the Enlightenment and sometimes coexists with pantheism, which is the perception of an omnipresent but impersonal and non-interventionist god.
Polytheistic religions, such as Hinduism, are among the world's oldest faiths. Many polytheistic pantheons conceive of gods who are not all-powerful but are the embodiment of a specific concept, such as war, love or good luck. Some polytheists primarily worship a single god from the pantheon, elevating the worship of a single deity almost to monotheism.
Monotheistic religions claim the greatest number of adherents in the modern world. Christianity and Islam between them have over half of the world's population as followers. Judaism is also monotheistic, but its followers tend not to seek converts actively, so it is followed by fewer people than the other two large monotheistic religions.
Islam is firmly monotheistic, with few, if any, adherents who believe in more than a single god. Christianity is generally regarded as monotheistic, though a majority of Christians, Catholic and Protestant alike, conceive of God as a Trinity.