Hinduism is the world's oldest religion, according to many scholars, with roots and customs dating back more than 4,000 years. Today, with about 900 million followers, Hinduism is the third-largest religion behind Christianity and Islam. Roughly 95 percent of the world's Hindus live in India. Hinduism is an Indian religion and dharma, or way of life. It is the world's third-largest religion, with over 1.25 billion followers.