Religion makes for a lovely pretext for people who want to steal and to kill. They can convince themselves that rather than indulging their own selfish, evil desires, they're doing something for God.
Take away God, and they just find some other "higher cause" to rationalize their actions. See Century, 20th.
Hitler was not a Christian. He did the politician thing and used Christian rhetoric in his rise to power. His religion once in power was a strange blend of Nordic paganism and a revision of Christianity where Jesus was an Aryan anti-Semite white supremacist.
The Crusades did not save Western civilization from Islam. The Fourth Crusade made it really easy for the Ottomans eventually to conquer the Balkans because the Crusader sack of Constantinople irrevocably crippled the Byzantine Empire.
The key battles that staved off Muslim advance were: 1) Tours, 2) the Reconquista, 3) Vienna.
Saying the Crusades are the reason Muslims hate Westerners now is stretching the definition of "reason" beyond recognition. The last of the Crusades happened over 600 years ago. People who hold grudges over things that happened 600 years ago are insane.
Western civilization as we know it is saturated with Christian ideals of morality, even if the piety itself is dying out. Everything about the West, good and bad, happened in a Christian framework from about A.D. 400 until World War I. Picking out the atrocities and saying they are the only thing religion influenced or caused is just cherry-picking.
Jesus was a homeless itinerant preacher with a background in manual labor, probably stonemasonry (he's called a "carpenter," but they didn't build wooden buildings there then). He was dependent upon the hospitality of his followers. It is profoundly unlikely that he himself owned slaves.
The Old Testament specifically allows chattel slavery of foreigners. It allows indentured servanthood of Israelites until the subsequent Year of Jubilee. In the New Testament, slavery is neither vouched for nor condemned as an ins ution. It simply exists.
The scholarly Greek New Testament that exists today is compiled from extant manuscripts from late antiquity, i.e. the late first to mid-fifth centuries. It is not some bas ized version reflecting 1500 years of editing. The Catholic Church in the fifteenth and sixteenth centuries didn't fool the people by giving them a heavily revised Bible that matched their new teachings. They fooled the people by hiding the Bible from them.
Pastors that collect peoples' hes and use them to buy million-dollar homes and Bentleys are going to burn in .
Yes, communities of faith are supposed to do good works. The idea of people doing organized acts of charity for people they don't know did not exist in the West until Christianity came along.