the previous posts are ‘definitive’ in answering the more obvious questions. As one of the links graciously provided above points out, Luther wanted to reject books of scripture that supported Catholic doctrine and practice.
There definitely were problems in the Church of the 16th century, which had been obvious for a century or more.
Luther rejected the authority of the Vatican, and pursuaded others to do so. That was attractive because it caused money, land, and power to be retained by nobles who were jealous of Rome. Luther also rejected the history of the Church, to which the authority, power, and money were linked.
Today, especially in the U.S., anti-Catholicism is still strong and it involves rejecting anything that the Catholc Church says, or so it seems to me. Heck, we can’t even agree on the 10 Commandments or the Lord’s Prayer.
Some evangelicals rail against Halloween, as symbolizing worship of spirits. There is obviously a deep intellectual obstinacy fueled by scandals in the Roman Catholic Church, no doubt.
Only the biggest scandal of sexual abuse comes to most people’s minds, but we have other scandals that are simmering, such as the widespread rejection of the Catechism of the Catholic Church by those who have been labeled “Neo Modernists.” They, too, like Luther, find the magisterial authority of the Church to be odious. Watch, and you will see that they are blooming neo-fundamentalists. They appeal to modern scripture studies as overthrowing vast areas of Church doctrine. It is a type of protestant reformation going on INSIDE the Church.