“Then as now, a buoyant market throve on fear. The Roman Catholic Church was a bank whose capital was secured by the infinite mercy of Christ, Mary and the Saints, and so the Pope could sell indulgences, like checks. The sinners established a line of credit against bad behavior and could go on sinning.”
Just as an aside, this is not what indulgences are or were (Amazingly, Wikapedia is quite accurate on this subject).
http://en.wikipedia.org/wiki/Indulgence