Head of Faith
A Head of Faith is the formal leader of a Faith. The powers and nature of the Head of Faith depends on the doctrines and tenets of that particular Faith. A Faith is not required to have a Head of Faith. The Faiths that do have a Head of Faith can have either a Spiritual Head of Faith or a Temporal Head of Faith.
Temporal Head of Faith
Temporal Head of Faith characters act much like a normal Ruler, with the Head of Faith Title being destroyed should they lose all their land. One example of this type of Ruler would be the Pope for Catholics. Should the Doctrines of the Faith allow for a Great Holy War, they will be considered a Directed Great Holy War.
Spiritual Head of Faith
Spiritual Head of Faith characters are Theocratic and do not have to be Landed, although they can be. Theocracy is an unplayable Government Form available for some Faiths depending on Doctrines. They are usually lead by a Head of Faith or a Landed Realm Priest.
Spiritual Heads of Faith usually carry additional benefits such as the access to interactions that include being able to grant Claims or Gold. Should the Doctrines of the Faith allow for the Great Holy Wars they will be considered Undirected Great Holy Wars.
Head of Faith Succession Law
Rulers who are also Heads of Faith have an additional realm Succession Law requiring their Heir be of the same Faith as them. This can never be changed, and Head of Faith Titles cannot have separate Title Succession. The only way to remove this type of realm law is for an external force to destroy the Head of Faith title.