What was Martin Luther trying to do to the Catholic Church?

There were (and are) abuses of power by the Catholic church, such as the selling of indulgences and immorality on the part of the church hierarchy.

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Catholic AnswerMartin Luther attached the Catholic Church because of sin, mostly his own. He was an Augustinian Friar under solemn vows (which he had made voluntarily after years of prayer and reflection) of poverty, chastity, and obedience. He left his Order without even asking for permission or a dispensation from his vows, and proceeded to flaunt all of them - in a rather spectacular fashion. M. Luther had severe problems with Christian morality and rather than repenting, believing in the power of Christ to save him; he rewrote Christianity into something else (now called Protestantism and Lutheranism) in which he didn't have to live by the Gospel and could claim he was saved despite himself. He attacked the Catholic Church in an attempt to deny responsibility for his actions.

from

Radio Replies, by Fathers Rumble and Carty, 1942

221 The power of Romanism was shattered by Martin Luther, of immortal memory.

Martin Luther is undoubtedly an outstanding figure in history. But the immortal memory of Luther will become less and less pleasant as the facts concerning him become known. Those who idealize Luther can do so only by ignoring an immense amount of inconvenient information. He was a priest of the Catholic Church, but one who was not faithful to his obligations even as a Christian. On his own admissions he was a victim of both immorality and drunkenness; and he was the most intolerant of men. Far from granting liberty of conscience, he refused to allow anyone to think differently from himself, and coolly said, "Whoever teaches otherwise than I teach is a child of hell."