Suddenly, he’s not such an easy man to categorize, is he?
The flaws of great men of history reverberate just as much as their successes, and I think that is true of Luther. I accept that he was a true Christian, and like all men deeply flawed. His flaws of pride and temper caught up with him later in life, just as King David's weakness towards the fairer sex caught up with the man after Hashem's own heart. Luther was also simply a reflection of just how much anti-Semitism had infected the Christian community over the millennia since Nicea.
You can no more disown the sins of Christianity's past with the "no true Scottsman" fallacy than the Jews can disown the sins of our own.
Shalom.