Who founded the faith on a ritual-free, simple "Sat Shri Akal" or the worship of God and truth?

The founder of Sikhism, Guru Nanak (1469-1538), was one of the best preachers and reformers in medieval India. He was critical of idol worship, pilgrimages, caste differences and the ceremonial frills of religion. Nanak founded his faith on a ritual-free, simple “Sat Shri Akal” or the worship of God and truth.