I recognize and am saddened by Martin Luther's hand in the peasant's revolution and noted it on my original posting. This is generally regarded by all parties as a black spot in his career. What I was trying to get at was the notion that his support of that uprising was already present in kernel form before he was excommunicated. I don't know whether this is true or not. But Luther certainly was a heretic by Catholic definitions - as early as 1515.
History is never that simple.
It is my understanding that an earlier reformer John Hus of the Unity of Brethren was burned at the stake as a heretic about 100 years earlier at the Council of Constance. The pope is thinking of offering some sort of apology concerning this, as I understand it. The whole subject of capital punishment for heresy is exceedingly complex. They are historically derived from Hus and his movement, but somewhat indirectly. They actually formed about 300 years after Hus's death.