La Religión del Katipúnan is a foundational historical and political work by Filipino patriot and intellectual Isabelo de los Reyes (1864–1938). The full title suggests a philosophical defense (Tediceea Filipina or Theodicy) of the Katipunan, the revolutionary society that initiated the Philippine Revolution against Spanish colonial rule in 1896. This book, originally published earlier and re-issued in this 1914 second edition, analyzes the principles of the Katipunan and its role as the "Association of the Children of the People" (Asociación de los Hijos del Pueblo). It is particularly significant because it claims to contain a previously unpublished "Second part" (Segunda parte inédita) detailing the organization, secrets, and fundamental principles (principios fundamentales) of the Katipunan's modern "Bathalism" and its democratic morals. The work is a critical primary source for understanding the ideological underpinnings of the revolution, Philippine socio-political thought, and de los Reyes's influential role as an author, publisher, and founder of the Iglesia Filipina Independiente and the first labor union in the Philippines.
La religión del Katipunan: ó sea la antigua de los filipinos, tal como ahora la resucita la Asociación de los Hijos del Pueblo (Katipunan) la promovedora de la Revolución