The precise number of religions in the world is not known, but available estimates show the number to be about 4,300, according to Adherents.com. Only two religions can claim more than one billion adherents each. Christianity has approximately 2 billion and Islam 1.3 to 1.5 billion believers.
According to Adherents.com, around 1.1 billion people identify as agnostics, atheists, nonreligious or secular. This number is higher than the estimated number of adherents of Hinduism, the third largest religion. Around 900 million people are Hindus. Chinese traditional religions have approximately 394 million adherents, Buddhism has around 376 million and primal-indigenous religions 300 million. Well-known religions with significantly fewer adherents include Sikhism, Judaism, Jainism, Shinto and the Baha'i faith.