Besides a recovery of the true gospel…
It seems that the start of getting people and nations to not be so reliant on a central authority (the Pope) and start governing for themselves. Yes, there were still monarchies, but the trend toward self-governance and democracy was really pushed forward and made possible by the Reformation.
To add to that, there were even cases where a push for religious reform led directly to political reform, like the English Civil War.
Tolerance of other beliefs within Christianity and interpretations of the Bible
That unfortunately took quite awhile to get to. The baptists had a lot to do with religious freedom since they were almost always persecuted by the more dominant views.
Roger Williams and the founding of Rhode Island was a big leap forward in that regard.
