Most churches serve a single deity. There are, however, churches whose priests serve multiple or all gods. The deities and their portfolio can be found in the DnD 4E Player’s Handbook, page 20 onwards.
The five most revered deities are known as the Big Five. They are Avandra, Bahamut, Moradin, Pelor and the Raven Queen. Erathis is also known as the Golden One, since his teachings ushered in the Golden Ages. The Lesser Five deities are Avandra, Corellon, Ioun, Kord, Melora and Sehanine. And last, the Evil Eight are Asmodeus, Bane, Gruumsh, Lolth, Tiamat, Torog, Vecna and Zehir.
Many Windyans are trying to teach the Arcadans about their gods. This practice is known as the Enlightenment Campaign.