The early Christians were primarily part of Judiasm, and later came from the Roman Empire. There was also a strong ethos of pacifism that is associated with the early church. I haven't heard of much violence in the early church so what are you referring to?
After Constantine made Christianity the Official State Religion, Christians were no longer fed to the lions in the Coliseum. Pagans took their place, their temples were destroyed, vandalized, or converted to Christian Churches.
Other examples can be found in the spread of Christianity by the early missionaries. When the kings of the Scandinavian countries converted to Christianity, it wasn’t because they “saw the light” in a religious manner, but because of the benefits of trade with central and southern Europe. Any of their subjects that continued their pagan ways were converted by the sword.
Look at the pogroms and witch hunts. Look at the wars between Catholics, Protestants and other “heretics”.
I am not criticizing Christianity, but being honest about its roots.