According to India's census, as of 2011 there are 138,188,240 Muslims in India. That equates to roughly 13.4 percent of the country's population, which at the time was over 1 billion people, making Islam the second most popular religion in India as of 2011.
India has been the country of origin for several notable religions, including Hinduism, Buddhism, Sikhism and Jainism. This is a big reason why India is home to a diverse array of religions. Of course, a vast majority of the country, roughly 80 percent as of 2011, practices Hinduism. The third most popular religion in India, as of 2011, is Christianity at roughly 2.3 percent of the country's population.