There is a world of difference between the community of Christians, which the Bible calls the Church - made up of every true believer in the world today and in all past ages - and Christendom (which we'll define for this blog as the marriage of the word "Christian" and the word "kingdom", meaning earthly kingdom.)
Christendom, is any grouping that calls itself "Christian" but possesses political power. A Christian who is a politician isn't necessarily part of Christendom - that may be his or her life calling from God. But a bishop who sits in the house of Lords, and wields political influence because of instituted religious power, is.
From the days when the Roman emperor Constantine "became a Christian", Christians began to confuse the church and the state. From then onwards they began to wield political power over unbelievers. Time came when over generations these religio-political leaders ceased to be true believers and they began to abuse their power and use it to oppose unbelievers.
From this confusion the name of Jesus has been dragged through a thousand pools of mud as He has been associated with the Crusades, Witch Hunts, Inquisitions, and numerous other atrocities.
In fact it is probably impossible to speak favourably of the name of Jesus to a secular historian, before first denouncing the heinous crimes committed in the name of Jesus. We need to explain that true religion can go to seed - and in Christendom is certainly has. We need to explain that we find true Christianity in Jesus and the New Testament, not in Christendom.
We need to disassociate ourselves completely from all alliances with political power, for Jesus said that his kingdom was not of this world, and Jesus told Peter to put his sword away, and Jesus went to his death rather than calling down angels to protect him.
Here's the way it goes:
In true Christianity, pagans persecute and Christians suffer.
In false Christendom, Christians persecute and pagans suffer.