According to this analysis by the journal Foreign Policy, these are among the fastest growing religions in the world.
Religion Adherents Growth Rate
Islam: 1.3b 1.84%
Bahaism: 7.7m 1.7%
Sikhism: 25.8m 1.62%
Jainism: 5.9m 1.57%
Hinduism: 870m 1.52%
Christianity: 2.2b 1.38%
The reason for the top five in the list: high birth rates in India and South Asia.
Congratulations, all ! (Especially to Hindutva adherents whose delight at the high growth rate of Hindus is matched by even higher rates for Muslims and the following explanation for the growth of Christianity- cause enough for some bashing up of the proselytizers)
…Pentecostal movements in Latin America, Africa, China, and India. The fastest-growing individual church in the world is Misión Carismática Internacional in Colombia; the Pentecostal denomination began in 1983 in Bogotá and now boasts 150,000 members. Then there’s Orissa Baptist Evangelical Crusade in India, which reports some 670,000 adherents.