I keep thinking the Crusades were started by Christians who wanted their land back after 700 years of Muslim rule. Imagine if the Indians decided to take the land back from us after about three hundred years of our rule. I don't think that was reasonable. If the Muslims had just taken over their land, then okay. Seven hundred years later? No. I would also count the inquizition.
But what I was mostly thinking of was the hundreds of years of theocracy in Christianity. A Christian's (and probably other religions as well) idea of freedom of religion was making their faith the state religion and persecuting anybody who wouldn't practice it. Your convictions should decide your faith, not the king or queen. People would persecute each other for not being Catholic, Protestant, or whatever. It's funny. We always hear about the Puritans leaving Britain to get religious freedom. Yeah, but they did, but then they either ran out or executed people who weren't practicing their faith. Rhode Island was the first colony in what's now America to have freedom of religion. Our founding fathers wanted the church and state separated because they understand what a religion ran country did to people. Actually, Uganda is the perfect example of a country being ran too much by religion. They have a new rule saying homosexuals can be executed. Not only that, but people who know a homosexual and didn't report can be punished by law. They're not doing that in the name of Islam, but Christianity. Bottom line is that religion shouldn't run the country. In theory, God would know what he's doing. In reality, it's faulty humans who run a country. So, I'm mostly talking about theocracy, not the Crussades or the inquizition.
The crusades were not about taking land back from the Muslims. Thet were about keeping the Holy places accessable and safe for pilgrims visiting them. Tha is not to say that, like in any war situation atrocities did not occur on both sides and that there was no one who tried to gain financially from them.
Forcing people to be Catholics was never an official or widespread situation in the Church. Isolated instances did, of course, occur. With the reformation, the new Churches and their political allies did act as you describe.