What is heresy?

Heresy refers to a belief or opinion that goes against the accepted doctrine or teachings of a religion or any other established system of thought. The term is commonly used in a religious context, where it refers to beliefs or practices that are considered to be false, harmful, or contrary to the teachings of the church. In the Christian faith, heresy was considered a serious offense and was often punished by excommunication or even death. Throughout history, various heresies emerged, challenging religious orthodoxy and leading to schisms, divisions, and conflicts within the church. Some famous examples of heresies include Arianism, Gnosticism, and Catharism. The concept of heresy also extends beyond religion and can apply to any established system of thought, such as political ideology or scientific theory, that is challenged by dissenting beliefs or ideas.