Martin Luther had raised the question of whether the practice and beliefs of the church of his time, as illustrated by the sale of indulgences, were truly Christian. He started a reformation in the church, taken up by Calvin, Wycliffe, Tyndale, Wesley and others.
This changed the church from a "works" related faith to a GRACE related faith!
We celebrated the reformation today.
We can rely completely on the grace and forgiveness we have through Christ and not on our own works.