What religion is the oldest in the world?

The oldest religion in the world is Hinduism. Also known as Sanatana Dharma, Hinduism is one of the major religions in the modern world with over a billion followers. Hinduism contains scriptures dating back 3,000 years ago, and roots and customs dating back over 4,000 years ago. As the world's third largest religion, Hinduism is referred to as a natural religion because of its universal applicability and ability to be understood through study, reason, and experience.