By God Alone achievement

Guido's Guiding Light

Starting as Archbishop Guido of Milan, become Antipope and make the Ambrosian Rite the mainline rite

Conditions in the game's words

The conditions name the character Guido (da Velate) — character ID et_milano_1066_1

Conditions as the game checks them

Possible decides whether the achievement can still be earned in a run; happened is the check that unlocks it (common/achievements/_achievements.info).

Unlocks when (happened) (6 lines of game script)

custom_description = {
	text = ce3_02_guidos_guiding_light_achievement_trigger
	this = character:et_milano_1066_1
	exists = global_var:ce3_02_guido_declared_antipope
	faith:catholic.main_rite ?= rite:ambrosian_rite
}

As written in game/common/achievements/ce3_achievements.txt.

Still possible while (possible) (1 line of game script)

this = character:et_milano_1066_1

As written in game/common/achievements/ce3_achievements.txt.

Source: game/common/achievements/ce3_achievements.txt, game/common/achievement_groups.txt and the English localisation, Crusader Kings III 1.20.0.3.