In a land of false prophets, a Lamb (nicknamed Lambert), supposedly the last of their kind, is brought before The Four Bishops of the Old Faith, and is sacrificed before them. Upon dying, The Lamb is brought before "The One Who Waits", a strange deity who is imprisoned in chains. The One Who Waits tasks The Lamb with starting a cult in its name, gives The Lamb a demonic crown, then resurrects them. Assisted by Ratau, The Lamb's precursor, The Lamb then settles at the ruins of a temple and begins establishing a cult on behalf of The One Who Waits, in order to defeat the four other Bishops – Leshy, Heket, Kallamar, and Shamura – and free it.
The player must launch roguelike-style crusades and venture out into the game's five regions to defeat enemies and grow their following. The world, which is randomly generated and contains roguelike elements, contains resources to gather, perks and weapons to collect, enemies in the form of rival cultists and non-believers to fight, and other animals to rescue; these animals can be indoctrinated into the player's cult. They have appearances that can be changed and both positive and negative traits, which can affect how they act in the cult or how they react to the player's actions regarding the cult.