Game concept · By God Alone
Zeal Chapter
The game also links it as Zeal.
From the game's encyclopedia
A Zeal Chapter stirs outward fire:
Mass conversions may take place, Great Holy Wars may become more common, Papal Bulls may be more frequent, and Faith conversion may be easier.
Conversion and Crusade are Zeal Chapters.
The game's text for patch 1.20.1.2. Words in blue are entries of the encyclopedia: hover one to read it, as in the game.
Zeal Chapter is an entry of Crusader Kings III's in-game encyclopedia (By God Alone). The game explains it: "A Zeal Chapter stirs outward fire:" It is part of Chapter Type. The game also links it as Zeal. Patch 1.20.1.2, from game/common/game_concepts/pam_game_concepts.txt and game/localization/english/game_concepts_l_english.yml.
Source: game/common/game_concepts/pam_game_concepts.txt, game/localization/english/game_concepts_l_english.yml and the English localisation, Crusader Kings III 1.20.1.2.