Not a true statement.
First off, Christianity was slowly replacing the Roman Empire (not by brutality, but by the teachings of the Christ). Then came the pillaging and plundering muslims, Turks, and Moors. That was the beginning of the "Dark Ages". It took hundreds of years to recover (sad, today, people are saying: we should embrace their way of thinking, their culture).
Christianity was points of light at that time for many. There were some really corrupt players that infiltrated the church then too. There were still pagan religions, human sacrifices, and some other nasties too! Then there was the belief that "royalty" had different rules than the "commoners". That was not changed until the Quakers gained prominence. The Quakers (a Christian faith), influenced the new gov't in this country, so there would be no special rules for those in gov't and the citizens that chose them!
Noticed how you skipped over the inquisitions
Or conquering native lands and forcing Christianity on the population by the sword like in Mexico and South America
Witch Hunts (beginning circa 1480 in Europe): The witch hunts in the United States were short lived and resulted in very few deaths compared to the witch hunts in Europe where countless people were wrongfully murdered after bogus trials for the cross.
The Crusades (Beginning 1095): As a religious driven military movement, the Crusades, fought mainly against Muslims, were efforts to recapture the “Holy Land” which lead to irrational claims of “crosses” appearing on chests of leaders, demoralization of non-Christians (Jews and Muslims) and mass murders of innocent men, women and children.
The Inquisition (Beginning 1184): The purpose of the Inquisition was stated in a 1578 handbook for inquisitors as, “… for punishment does not take place primarily and per se for the correction and good of the person punished, but for the public good in order that others may become terrified and weaned away from the evils they would commit.” Such as statement makes it clear that the goal was to inspire fear among a people in order to rule and conquer them. During the Inquisitions church leaders often supported the enslavement and/or murder of “heretics”.
The Holocaust (beginning circa 1933): Christian Fundamentalism was a primary cause of the Holocaust. Jewish persons had been murdered and enslaved throughout Europe’s violent Christian history and the Nazi’s continued this long tradition of murder – claiming it to be for the betterment of God and God’s wish. Although the Jewish people took the largest number of casualties, other groups were murdered including, homosexuals, Soviet citizens, political prisoners and the disabled.