Go back to where you left Erik before the attack, only for the priest to tell you he'd been taken by the enemy. Hit them with Sylvando's Fuddle Dance and they will all be confused if you're lucky. When the Vikings come to attack Sniflheim, go back to the city square and fight off a group of gold enemies. Check the map and there should be an NPC at the cliff to the west of the city. The conversation upsets Erik enough to want to be alone and the priest sends you after him. It's the building with a pink NPC in front of it.
After being told about the Gold Fever, return to town for a scene then go see the priest at the church by the entrance.
