Pope Leo X, who was pope from March 9, 1513, to December 1, 1521, excommunicated Luther.
It was Pope Leo X.
The pope and several Roman Catholic monarchs.
The RC Church treated him as a heritic and his life was threatened.
Martin Luther King did not challenge the pope.
Martin Luther was never made a representative of the pope.
The Pope issued a papal bull threatening to excommunicate Luther if he did not recant in 90 days. Luther is said to have burned copies of the bull. Luther was excommunicated and Holy Roman Emperor Charles V was told to kill him on charges of heresy. Charles summoned him to Worms (verms) to be examined. Luther was declared a heretic. Luther had thirty days to return home before being declared an outlaw. On the way back to Wittenburg Luther was kidnapped by his friend a prince of Germany. the prince took him to a castle where luther lived in safety and translated the New Testament into German. Because Charles was busy with foreign affairs Luther was not bothered for the remainder of his life which he spent mostly in Wittenburg.
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.
Pope John XIIII declared the 2000 Jubilee Year.
The pope excommunicated Luther because his teachings were heretical.
He was not a threat at all to the pope
Pope Julius I
Pope John Paul II declared Juan Diego a saint.
The Pope during Martin Luther's posting of the Ninety-Five Theses was Pope Leo X.