Catharism (from Greek: katharoi, "the pure") is a Christian dualist movement that thrives in some areas of Southern Europe, particularly northern Italy and southern France, between the 12th and 14th centuries.

Cathar beliefs vary between communities because Catharism is initially taught by ascetic priests who set few guidelines.

The Cathars are a direct challenge to the Catholic Church, which renounces its practices and dismisses it outright as the Church of Satan.

Catharism has its roots in the Paulician movement in Armenia and the Bogomils of Bulgaria, which had taken influences from the Paulicians.

Though the term "Cathar" has been used for centuries to identify the movement, whether the movement identified itself with this name is debatable.

In Cathar texts, the terms "Good Men" (Bons Hommes) or "Good Christians" are the common terms of self-identification.

The idea of two Gods or principles, one being good the other evil, is central to Cathar beliefs.

The good God is the God of the New Testament and the creator of the spiritual realm, as opposed to the bad God, whom many Cathars identify as Satan, creator of the physical world of the Old Testament.

All visible matter, including the human body, was created by Satan; it was therefore tainted with sin.

This is the antithesis to the monotheistic Catholic Church, whose fundamental principle is that there is only one God who created all things visible and invisible.

Cathars think human souls are the genderless souls of Angels trapped within the physical creation of Satan, cursed to be reincarnated until the Cathar faithful achieve salvation through a ritual called the Consolamentum.

From the beginning of his reign, Pope Innocent III attempts to use diplomacy to end Catharism, but in the year 1208 Innocent's papal legate Pierre de Castelnau is murdered while returning to Rome after preaching the Catholic faith in southern France.

With the option of sending Catholic missionaries and jurists extinguished, Pope Innocent III declares Pierre of Castelnau a martyr and launches the Albigensian Crusade.