The Faith is the predominant religion in the Western Kingdoms. This polythiestic religion believes that by currying enough favor from the Gods, a person could be granted favors and can even be spared from death.
One of the greatest heresies in the Faith are magics performed outside of the Covenant, a pact made with the gods that governs all use of magic in the Western Kingdoms.
History
The Elves of Ara have kept the Faith for the entire length of their recorded history. When the time came to overthrow Razenor, it was the half-elf prophet Caius who came to their aid. He offered the Kings of Men the choice to accept the Covenant, a source of magic that derives power from veneration of the Gods, a power which would free them of the iron fist of imperial Razenor.
Thereafter, a clergy was established - with elves in key positions - to help govern and guide the humans in their new faith.