Martin Luther King did not challenge the pope.
Martin Luther was never made a representative of the pope.
The Pope during Martin Luther's posting of the Ninety-Five Theses was Pope Leo X.
He was not a threat at all to the pope
Martin Luther stated he would only reconcile with the Pope if the Pope accepted his 95 Theses in their entirety. On meeting with the Pope, the Pope accepted only a fraction of them which caused Martin Luther to break with the Communion of Rome.
Martin Luther was not arrested, although a warrant was issued due to heresy against the Pope.
Pope John Paul II was a faithful Catholic Pope. Martin Luther was a heretical monk who separated from the Catholic Chuch and formed his own religion.
The Roman catholic pope excommunicated Martin Luther
Martin Luther was no pope, history tells us that he was a professed friar of the Augustinian Order, and that he had been ordained to the priesthood, before he left his Order, broke all his vows, and was excommunicated for heresy.
The Roman catholic pope excommunicated Martin Luther
Pope Leo X was accussed by Martin Luther of selling indulgences.
There may be some confusion here. The Catholic Church doesn't say that the Pope cannot make mistakes. They merely say that when he defines a Church doctrine in the name of the Church, and for the entire Church, his definition will not be in error. Since the Church doesn't CLAIM that the pope makes no mistakes, then, we should not expect Martin Luther to have used the idea as an objection to the Church.Source: http://oce.catholic.com/index.php?title=Infallibility