Clerics and Televangelists can sell indulgences, which adds happiness while draining gold from the target city, and sending it to the attacking Civilization. This attack is always successful and it's free.
Great Library entry[]
Historically, religions have depended on charitable contributions for sustenance and growth. In Western Europe the Catholic church was notorious for its form of acquiring funds. One of the most famous and the most criticized forms of generating revenues was through the sale of indulgences where priests would grant forgiveness of sins in exchange for cash. Chaucer in "The Canterbury Tales" poked fun at the sale of indulgences through the character, the Pardoner.