Faith builder: piety cost

How the cost is counted

Every doctrine and tenet you end up with has its own piety_cost formula in common/religion/doctrine_types and tenet_types. The formulas look at the faith you start from: keeping a doctrine or tenet it already has multiplies the cost by faith_unchanged_doctrine_cost_mult (0.5), moving two, three or four steps along a scale multiplies it by 1.5, 2.25 or 3.5, and some depend on the religion (a tenet is cheaper for the religions it belongs to). The values are in common/script_values/02_religion_values.txt.

Then the whole sum is reduced by the starting faith's fervor (rite_creation_cost_mult): the discount is 0.5 × min(100 − fervor, 50) ÷ 100, so a faith at 50% fervor or less makes creation 25% cheaper (NFaith and NRite in common/defines/00_defines.txt).

Not included: how many tenets a faith or rite may hold and the divergence that decides between a new rite and a new faith (those rules sit in the game's code), and the converting-to-a-faith cost. Conditions the calculator can't check count as not met: has_variable = accepted_cannibalism. Tenet and doctrine effects are on the tenets and doctrines pages. Game files of patch 1.20.0.3.