Why did Charles V, Holy Roman Emperor, in collaboration with the Pope, issue the Edict of Worms in 1521? What were the implications of this move?

The Diet ( Assembly) of Worms called together the Bishops of Germany to investigate the challenges to the Pope and the existing Catholic positions by Martin Luther. The edict of Worms was the conclusion of the religious assembly supported by the secular power of the Holy Roman Empire.

Martin Luther had called for the reformation of the Catholic Church. His famous 95 thesis were specific points that Luther felt needed to be changed in the Catholic Church. The Pope felt that the 95 thesis were a direct assault on his personal power and called for the thesis to be rejected. The Catholic counter reformation would later follow some of the "suggestions" of Martin Luther.

The Diet of Worms obeying the wishes of the Pope called for the rejection of all 95 thesis and for Martin Luther to recant and disavow his call for reformation. When Martin Luther refused to recant the Assembly excommunicated Martin Luther from the Catholic Church. Charles V as the secular ruler of the Holy Roman Empire was called on to support and enforce the rulings of the religious assembly. The edict of Worms was Charles V statement as to the excommunication of Martin Luther and a proclamation forbidding anyone to support or follow the teachings of Luther.

As Charles V needed the support of the Pope to retain his crown as Emperor, Charles V had little choice but to support the Diet of Worms and issue his Edict of Worms.

Many nobles in Germany refused to obey the Edict and provided Martin Luther with sanctuary and support. The printing presses published multiple copies of Martin Luther's teachings to the extent that the Catholic church was not able to repress the protestant movement. The result of the Edict was the split of Christianity into two rival camps the Protestants and the Catholic in western Europe.