The Upanishads and the Axial Turn in India
Along the Ganges, thinkers began asking questions that the older ritual religion of sacrifice could not answer: what is the self, what survives death, what lies behind the visible world. The Upanishads that recorded their arguments introduced ideas that would organize Indian thought ever after — karma, rebirth, and the identity of the individual soul with an underlying reality. They came from forest hermits and dissenting teachers, not the priesthood, and they shifted religion's center from performing a rite correctly to understanding one's own nature.
A belief system rises, spreads, institutionalizes, and then schisms — changing the rules people accept as legitimate.