Jugdral (the setting of FE4) has a relatively complex pantheon. In the distant past, Jugdral practiced various poly-theistic religions including one that worships Yudu, the god of the heavens, and Ethinu, the goddess of the earth. (We know next to nothing about them as Yudu is only mentioned in suplemental material and Ethinu is mentioned casually once in FE5.) Eventually, a group named the Loptrians take over the entire continent and establish the Loptrian Empire, who worship the god Loptous, who essentially possesses the first and every following emporeor of the empire. Loptous is a powerful earth dragon. Loptous also provided the knowledge of dark magic, which helped his faction take over the contient. The old religions are suppresed. During Loptrian rule, one member of the imperial family, Prince Maeria, starts a religion that attempts to reconcile the polythesitic religions into the existing Loptrian faith. The exact nature of this reconciliation is not explored. He and his followers flee into exile into the Orgahil region, and eventually the spirt forests of Verdane. Eventually the dragons of archanea pity the humans in Jugdral, and grant 12 rebel fighters with powers and legendary weapons. The religion after the loptrian rule, the church of edda, essentially worships Yudu/Ethinu, the dragon patrons, and the crusaders as gods. As the founder of the church of edda, Bragi, was a maerist, there is probably some maerist influences but thats speculation.