Well, would you then say that Buddha was Buddhist? Calvin was Calvinist, Jesus was Christian??? My simple point is that Luther was Roman Catholic and would have remained so if the Church had not excommunicated him. They certainly did make changes that he brought up but refused the main one on which they had gone off-track - salvation by faith alone. I, like him, could not remain knowing the truth from God's word either.
FYI - The followers of a person's teaching are called by the teacher's name, hence, Lutherans follow the teaching of Martin Luther; Calvinists, Calvin; Christians, Jesus Christ. The belief system was later named after the person. Do you get my point?
The original point was that Luther was a godly man and then when evidence was submitted that he was indeed an evil vile man by today's standards the argument changed into Luther being a Catholic. Luther was excommunicated because he disagreed with the teachings of the Church putting him outside of the Communion of the Saints. One cannot argue that Luther was Catholic and not a Catholic or that everything good about him was limited to his anti-Catholicism and everything bad about his is a result of his Catholicism.
Further, those extolling the godliness of Luther have all espoused significant differences with his dogma in many areas implying or specifically stating that the godliness is only derived from his opposition to the Catholic Church. That is a vacuous argument and reinforces that those participating in attacks on Catholicism are doing so out of a visceral hatred of the Church and not on points of theology or dogma.