False Prophets and True Believers

In many roleplaying games, prophecy is often associated with divination magic or world-shaking metaplots, but as the (non-)events of today demonstrate, prophetic pronouncements may be a source of challenges, hazards, and opportunities in historical campaigns as well. It's not hard to see how one could turn the examples of Sabbatai Zevi, Manoel Dias Soeiro, Popé, or the Fifth Monarchists into patrons or (possibly sympathetic) antagonists for a 17th century campaign.