The Barren Kingdoms
Religion in the Barren Kingdoms is not as varied as it is in some campaign settings. Rather than a polytheistic pantheon, Wealdan was long dominated by a duotheistic pair, Annya and Ramus, also called the Twins. They were widely worshiped in both Barien and Lioncourt, and even had adherents in Uduerinstand and Yn’yinlaris. Further, there was no clear god of evil in the world before the Great Dying; instead, those who were, in game terms, “clerics of evil alignments” were more akin to warlocks, having begun to worship evil extraplanar powers in return for arcane abilities. The “god” of death was the Tallyman.
After the Great Dying, many viewed the death of humanity as a great failure on the part of the Twins, who were the patron deities of humanity, and worship diminished. Remaining clerics of the Twins (mostly fairekin and duerkin) found themselves without divine abilities.
Instead, four minor powers of the world, the so-called Guardians of the Cycle, rose to prominence. In an uncertain world, they were viewed as being a sure thing — the never-ending turn of the seasons, and the representatives of the basic needs of society. As these minor deities also granted divine powers, they became increasingly popular, especially in Freehold and the Reclaimed Lands.
In addition to the Twins and the Guardians, both the duer and the fyrell have their own patron deities. For purposes of this campaign, these deities are Moradin (duer) and Correllon Larethian (fyrell), as described on page 296 of the PHB.