The Kdaptists were a religious order, often characterized as a cult, that formed among the ranks of the Kzin towards the end of the First Man-Kzin War. Kdaptists were named after the founder of their sect, Kdapt-Preacher, who had formerly been known as Kdapt-Captain.
The religion of the Kzin Patriarchy taught that the Kzin were created at the top of nature's hierarchy, having been made in the image of the Fanged-God. All other species were there to be conquered and enslaved. Before encountering mankind the Kzin had easily defeated every species that they had made contact with, reinforcing their belief in their divine destiny. It was only after the humans defeated several waves of Kzin invaders and even began to stage effective counterattacks of their own that doubts began to form in the minds of some Heroes.
Towards the end of the first war, a Hero called Kdapt-Captain was imprisoned by an artificial intelligence equipped ship named Catskinner which had been sent to Wunderland as part of an ARM mission. The Catskinner kept Kdapt-Captain in darkness, with only the smell of rotting corpsese to keep him company, and no food or water, for several days. A human kept in such conditions would have gone insane, if it survived at all. The Kzin as a species tended to be much more sensitive to the effects of sensory deprivation than humans, and the ordeal had a profound impact on Kdapt-Captain.When he finally was released the crazed Kzin began to espouse a new vision of God that he claimed to have visited him during his captivity.
After his religious experience, Kdapt-Captain changed his name to Kdapt-Preacher and moved to the newly liberated Wunderland. He lived a nomadic lifestyle, wandering from place to place and preaching his bizarre religion to any Kzin that wold listen. His teachings, which at one time would have been considered as nothing short of blasphemous, found fertile ground in the minds of battle-scarred Heroes who were desperate to find an explanation for their sudden reversal of fortune. Kdapt-Preacher taught that God made Man, not Kzin, in his own image. God had made the Heroic race with respect, but he had made humans lucky, and for whatever reason he was coming to favor them over the Kzin. Over time, the Kdaptists split into two competing factions. The High Kdaptists believed in fully cooperating with the humans in accordance with the will of God. The Low Kdaptists began to use masks and garments made of human remains in an attempt to trick God into granting them favor. The use of human remains as religious artifacts was one of the more notorious aspects of the Kdapt religion, leading to allegations of human sacrifice and giving the whole sect a somewhat sinister reputation.
The infighting between the different factions was effectively put to an end by Vaemar Riit and his followers in league with the UNSN and Free Wunderland armies, although the religion itself continued for some some time afterwards.
By the time of the events in Ringworld, Kdaptism has become a minor, if not tolerated, religion. Speaker-to-Animals tells Louis Wu that he was raised by a Kdaptist, but claims not to share their beliefs.