Final answer:
The main heresy of Albigensianism related to dualism, which is the belief in two opposing deities or forces. Albigensians rejected many aspects of the Catholic Church's teachings and emphasized asceticism and the denial of worldly goods.
Step-by-step explanation:
The main heresy of the day of Albigensianism was a form of dualism.
Albigensianism was a religious movement that emerged in the 12th century in southern France. The Albigensians believed in the existence of two opposing deities, one representing good and the other representing evil. This dualistic belief system led to their rejection of many aspects of the Catholic Church's teachings, including the material world and the sacraments.
An example of a dualistic belief within Albigensianism was their view that the physical body and everything associated with it was inherently evil, while the spiritual realm was good. This belief prompted them to adopt ascetic practices and reject worldly possessions.