Game concept
Tenet Popularity
From the game's encyclopedia
As Personal Tenets spread within a Faith their practice becomes more common. Tenet Popularity tracks how widespread a Tenet is and affects how likely it is to be picked as debate topic in an Ecumenical Council or as a target of a Papal Bull.
The higher the Tenet Popularity, the more the Clergy will side with a tenet when it is debated in an Ecumenical Council. Once a tenet reaches 2000 Tenet Popularity, the Head of Faith will most likely declare it Permitted no matter their own convictions.
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.
Tenet Popularity is an entry of Crusader Kings III's in-game encyclopedia. The game explains it: "As Personal Tenets spread within a Faith their practice becomes more common." It is part of Tenet Status. 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.