A heretical schism of the Universal Church of the Celestial Sun.
The origins of the Incarnate religion originate in a liberal sect of the Universal Church in the Second Republic era called Eurygnostics, who preached the Universal Heterodoxy, which stated that sentients as well as the Pancreator had a spark of the Holy Flame; and also taught that Church laity as well as clergy could study and interpret the Omega Gospels for themselves. The Eurygnostics also were willing to mix religion and politics. The archbishops of Gwynneth were the official heads of this official Church order. After the Fall of the Republic, the Eurygnostics were dissolved by the Universal Church, Gwynneth started to get Orthodox archbishops, and Eurygnostic-leaning clergy were absorbed into the Orthodoxy or official Hesychast sects.
The Eurygnostic remnants were partial absorbed by the Mahayana wing of the Orthodoxy, but a late 42nd-Century Orthodox cleric named Zarek Mazentius would transform the remainder of the Eurygnostic remnants in the church into the Incarnates. A rebellion on Gwynneth by Zarek and Eurygnostics that included serfs and dissident nobles ended with a number of Eurygnostic clergy removed from the Church and with Zarek starved to death in a cage hanging from the ceiling of a Hawkwood palace. The Incarnates official seceded from the Universal Church in 4212 after spreading to various parts of the Known Worlds, including but not limited to Midian, Malignatus, and the Lost World of Iver.
The Incarnates were declared heretics by the Church Patriarch in 4233 and thereafter hunted by the Inquisition. In the 47th Century, the Incarnates revived under the leadership of Bishop Thurlow, but he perished attempting to seize the Universal Church's planetary cathedral on Madoc. By the 50th Century, the Incarnates were largely suppressed, especially on the Li Halan worlds, but in the latter half of the century, during the Emperor wars, a former Orthodox cleric named Annika assumed leadership of the Incarnates and revived the religous movement, but she was killed on Malignatus in 4978 by Li Halan knights with the approval of the Church Patriarch Hezekiah. The Incarnates today still preach their version of the Omega Gospels, which is printing in Urthish instead of Latin with the Universal Church's version of them. The Incarnates have religious ranks no higher than bishop, with leadership of the sect by a council of bishops.