Manichaeism was a widespread religious movement founded by the third-century Iranian prophet Mani (216-276 CE).
Based on his alleged angelic revelations, Mani proclaimed himself to be the last in a line of great prophets:
Heavenly revelations aside, a more worldly historian of religion would say that Manichaeism was a syncretic religion drawing on several pre-existing sources, to include Gnosticism, a force to be reckoned with in late Antiquity.
Mani believed the side of “light” would eventually vanquish the forces of “darkness,” delivering mankind from the bondage of worldliness.
Manichaeism was no isolated movement but belonged within thriving communities that juggled various political and religious forces.
St. Augustine of Hippo said in his Confessions that he was duped into following Manicheism until he studied the available astronomical calculations of the era. The empirical figures contradicted the cosmology of the Manichean books, which were “full of the most tedious fictions about the sky and the stars, the sun and the moon.”¹
So Augustine confronted a Manichee called Fautus who, says Augustine, was “obviously unable to settle the numerous problems which troubled me.”
The Manichaean Church was made up of the elect ‘righteous’ and auditors (‘hearers’) and grew to the extent that it rivaled Christianity.
Believers hoped to facilitate the reorganization of particles of light or, at least, not hinder this process. Through their alleged wisdom, they saw themselves as contributing to the triumph of light over darkness.
Mani himself came to an unfortunate end. After enjoying political support from previous heads of state, the Zoroastrian Bahram I persecuted the Manichaens. Mani was imprisoned and brutally executed.²
After centuries of persecutions from Christians and non-Christians, Manichaeism is virtually non-existent, save for a few small groups claiming to uphold this religion.
¹ Ironically, the Christian Church which Augustine championed came to ignore and repress most cosmological innovations in the Middle Ages. Daniel Boorstin says in The Creators that, instead of looking at scientific attempts to measure the Earth, Christian cartographers drew up wildly imaginative fantasies that a contemporary depth psychologist would have a heyday with.
² The grim details – https://en.wikipedia.org/wiki/Mani_(prophet)#Life