Top Ten Religions of the world:

Christianity: 1.9 billion (1 in 3)
Islam: 1.1 billion (1 in 5)
Hindu: 781 million
Buddhist: 324 million
Sikhs: 19 million
Jews: 14 million
Baha'i: 6.1 million
Confucianism: 5.3 million
Jains: 4.9 million
Shinto: 2.8 million

Top Religions of the US (Christianity split somewhat):
Protestant: 56%
Roman Catholic: 28%
Jew: 1%
Everything else: 15%

Source: Information Please Almanac
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"Nature has constituted utility to man the standard and test of virtue. Men living in different countries, under different circumstances, different habits and regimens, may have different utilities; the same act, therefore, may be useful and consequently virtuous in one country which is injurious and vicious in another differently circumstanced" - Thomas Jefferson, moral relativist