In a mature religious society, it becomes inevitable that a drive to change manifests itself at some point. As religious practices stagnate and become too gaudy and empty of spirit, people start clamoring for a reform. And this Reformation brings about new life in their main Religion - a new Belief which is so strong that may potentially alter the course of your empire!
- If you founded a religion, gain a bonus Reformation belief.
The uber-Policy of the Piety tree, Reformation lets you choose the most powerful Belief of your religion. The possible choices are all aimed either at providing a really powerful all-around bonus, or one targeted at a specific victory path. However, just as with other Beliefs, they are available on a first-come, first-served basis, so you should aim at rushing this Policy (so, open up the Tree, then adopt Organized Religion and Religious Tolerance).
Note that the extra Belief can only be adopted after you found a religion! If you have already founded one (even if it's not enhanced), you may choose the Belief already. If not, you will have to wait until you manage to found a religion. This delay could sometimes cost you the very choice you intend to pick! So, do all in your power to found a religion before, or immediately after you adopt Reformation.
The specific choice will depend on many factors. Look to the Victory strategy articles for more guidelines of how to choose.
Reformation refers to a great movement to reform a religious organization or belief system that is seen to have become corrupt or to have strayed from its guiding principles. The "Protestant Reformation" was a movement to reform the Roman Catholic Church. Begun in 1517 when Martin Luther published "The Ninety-Five Theses" listing the Church's transgressions as he saw them; the movement sparked some 130 years of horrible, bloody religious warfare across Europe and in the New World. As a result, Christianity was permanently fractured into various different organizations and civil authority gained ultimate primacy over religious life.