A commenter at Beggars All, “steelikat,” posted this link — “Who split the Church?” — and I agree with him, “it’s a good thing that ‘the church’ is split.”
Luther was excommunicated. Why? Because he criticized the sale of indulgences. In the case that precipitated his nailing the theses to the door, a salesman named Tetzel was participating in a manifestly corrupt venture–having to do ecclesiastical bribery and simony–that was theologically untenable…
It was penal fire that people were taught might last hundreds, even thousands of years. (7 years per sin; do the math.) And this was for sins that were forgiven! Sins that were repented, confessed, and absolved STILL had to be punished.
Luther believed this teaching and this practice obscured the Gospel. He just wanted to debate it! His attempts at reform were repudiated.
The Church of Rome, meanwhile, upped the ante. Luther said that these teachings could not be supported by Scripture. The reply was that they rested on the authority of the Church and of the Pope, which, in practice, trumped Scripture. Luther, still thinking of the obvious distortions in the indulgence traffic, could not accept that.
So Luther was cast out of the Church, which refused to even consider his concerns, and things escalated after that. Luther was given a death sentence, and many who agreed with Luther were burned at the stake.