The main religion practiced in the Roman Empire was polytheism, primarily centered around the worship of a pantheon of gods and goddesses. Key deities included Jupiter, Juno, Mars, and Venus, among many others. Religious practices were often tied to state rituals, with emperors themselves being deified after death. Over time, the Roman Empire witnessed the rise of mystery religions and philosophies, but the most significant shift occurred with the acceptance of Christianity in the 4th century AD, leading to its eventual establishment as the state religion.