Game concept

Pious Building

The game also links it as Pious Buildings.

From the game's encyclopedia

Pious Buildings are Buildings whose primary function is to increase their holding's Piety.

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.

Pious Building is an entry of Crusader Kings III's in-game encyclopedia. The game explains it: "Pious Buildings are Buildings whose primary function is to increase their holding's Piety." It is part of Building. The game also links it as Pious Buildings. Patch 1.20.1.2, from game/common/game_concepts/00_game_concepts.txt and game/localization/english/game_concepts_l_english.yml.

for a guide, post or blog

Source: game/common/game_concepts/00_game_concepts.txt, game/localization/english/game_concepts_l_english.yml and the English localisation, Crusader Kings III 1.20.1.2.