That's not quite true.
The term Protestant is taken from the "Protestation at Speyer" when a group of German nobles aligned with or sympathetic to Martin Luther signed a letter that began with the words, "We protest" to the Holy Roman Empire's decision to basically destroy Lutheranism.
Do I agree with what Luther did? No, but I have always admired his conviction. Luther's "95 Theses" addressed many LEGITIMATE areas of corruption in the Church, things that have long since been corrected. The Church NEVER sanctioned the sale of indulgences, but a great many in the Church also looked the other way when it happened. There were things that NEEDED to be addressed and it is unfortunate that the outcome was what it was. I have long believed that Luther's desire WAS NOT to divide the Church, but I think he was pressured by a noblemen who had a great deal to gain by having a German Church that was was not subject to the Vatican.
The Augsburg Confession is the fundamental to the Lutheran Church and it is something that Catholics should certainly understand. In the mid-1970s, Pope Benedict XVI expressed his belief that it could possibly be seen as a Catholic document. However, the Augsburg Confession was rejected by other Reformation leaders and this lead to the the division among Protestants.
So basically, I think it is wrong of us to lump Protestants together. While we have our differences, I believe that Lutherans, Anglicans and many who come from this tradition truly are united with Catholics in our belief in One, Holy, Catholic and Apostolic Church.
He also said that he would love to sit down and have a meal (or a beer) with Luther, but Calvin did not seem to be the type of guy you wanted to visit with.
The big problem that set the Lutheran Reformation off was that neither side was really interested in what Luther was saying at times. The Pope didn't really care at first what some back woods Augustinian monk said from one of the Germanies, and the Elector Princes just saw a way to tell the Pope to get out of their hair. By the time the split happened, it was more political than theology.
Same with the horror that was the 30 years war. There was a Catholic poster here on FR that mentioned a Lutheran (Protestant) army sacking Rome. I was at first confused, for no army of the Protesting Estates made it that far south. We were both right. The army was a mercenary one under the Catholic king of Spain Charles V, who was fighting with the Pope over who would rule. In the end, most of the fighting over the 30 years was financed by Catholic powers arguing over the Imperial throne. Religion was a side issue.
Catholics and Lutherans have much shared theology. So much that while we are the “original” Protestants, using that term leads to much confusion on both sides.