Religions of the Storm Coast
There are perhaps hundreds of faiths in the world, but for the purposes of this we will consider only those in the Storm Coast and only the three major faiths.
The Suulian Orthodoxy
Presided over by the Archbishop of Suul, Suulian Orthodoxy is a strictly organised monotheistic religion that believes in one god (God). They don't deny the existence of other gods, they just rebrand them as demons and pagan spirits and attempt to convert or burn those who think otherwise. Suulian Orthodoxy preaches kindness, justice, humility and fairness to followers, and quick, fiery deaths and retribution to those who aren't.
Suulian Orthodoxy is most favoured along the Mirish Coast, and has fairly strong sway in the western Republic of Groan.
The Mounish Heterodoxy
Mounish Heterodoxy is a slightly more loosely organised religion that schismed from the Suulian faith about two hundred years ago. It preaches a pantheon presided over by God (the same God as the Suulian one), but with many lesser deities beneath it - unlike the Orthodoxy, the Heterodoxy acknowledges their full divinity. Many of the formerly independent gods of the Storm Coast have been incorporated into the Church's doctrine, presided over by the Archbishop of Moun.
Mounish Heterodoxy is strongly favoured in the city-states of the Storm Coast and somewhat in the Kingdom of Grune.
The Thousand Gods of Samakhet
Nobody knows exactly how many gods there are in the Samakhet Isles, but a thousand might not be far off the mark. Every island has its own pantheon of gods, and every village within has its own pantheon of demi-gods and local spirits. The religion is completely disorganised, and any one god likely only has one or two priests - some pay homage to many gods and act as their general spiritual representative. There are a handful of famous gods that persist throughout the myths of the Isles; Aegir the Drowner, The Sun-Rider and Dysentras, God of Cesspits are amongst these. (A common insult in the Storm Coast is to wish Dysentras to favour them with his presence.)
Apart from the Samakhet Isles themselves, the Thousand Gods are mostly favoured by sailors, who hold to the freedom and flexibility the faith affords. Thus followers and perhaps even priests of the Thousand can be found in any port across the coast.