In my opinion, the Church wouldn’t make him a Saint at all even if he didn’t leave the Church! At this time in history, Luther was upset about a lot of things the Catholic Church was doing wrong including the selling of indulgences. Since the money of the indulgences are going toward building what is know today as St. Peter’s Basilica in Rome (imagine, if you will, it being a huge “fundraiser,”) they thought that he was a heretic for speaking out against the church. Eventually, The Counter-Reformation came around and the Church defined and redefine Catholic doctrine (and in my opinion,) condemn Protestant teachings through the Council of Trent.