The priests Caypha and Anna give him letters to take to Damascus, where he is to suppress heresy (i.e. the worship of Jesus).

The novel is set in a parallel universe to ours, in a world controlled largely by a theocratic international organisation, the Magisterium (also commonly called "the Church"), which actively suppresses heresy.

The inquisitions in combination with the Albigensian Crusade were fairly successful in suppressing heresy.

Occasionally, the Imperium resorts to destroying entire worlds with weapons of mass destruction in order to suppress heresy, rebellion, or alien encroachment.

In his efforts to suppress heresy, Arundel had enacted laws that forbade allowing women to preach, for example.

Although the Inquisition was created to suppress heresy, it also occupied itself with a wide variety of offences that only indirectly could be related to religious heterodoxy.

As bishop's chancellor in Ely, Cambridgeshire, he was charged with suppressing Christian heresy, condemning several heretics to be burnt at the stake.

He strongly supported the use of force to suppress heresy and a strong alliance between secular and ecclesiastic authority in the use of force.

His reforms may have angered papal conservatives and led to the reconstitution of the Roman Inquisition as the Supreme Sacred Congregation of the Roman and Universal Inquisition in 1542 in order to suppress Protestant heresy.

Beginning around 1184, following the crusade against the Cathar heresy, various institutions, broadly referred to as the Inquisition, were established with the aim of suppressing heresy and securing religious and doctrinal unity within Christianity through conversion and prosecution.