^Actually there was infighting from the very beginning, even among the earliest gnostic communes. There is some evidence that evangelists like Paul and his followers eradicated other sects and that the Nag Hammadi cache was not being hidden from the Romans, but from other Christian groups.
Pagans were routinely persecuted and eradicated as the Word spread north into Europe, with few left to write their side of the story. It is believed at least hundreds of thousands of pagans died at the hands of Charlemagne's forces, who leveled not only their villages and shrines but whole forests and sacred groves in their campaigns. Then there's the atrocities and pogroms of the Crusades, followed by those of the Inquisition. The Reformation saw multiple Christian faiths jockeying for power with varying levels of brutality, the Church of England being just one of the more well known in the English speaking world for sanctioning the persecution of Catholics and atrocities against the Irish. (Happy St. Patty's Day!) And all the while, hundreds of thousands of dissident voices, homosexuals, 'uppity women', Jews, and any 'others' outside the favor of whichever group of Christians were in power at any given moment were burned, hung, drowned or tortured to death as witches and heretics. Even animals were occasionally tried and tortured to death, like the sow of Savigny, a mature mother pig hung upside down until dead after it had defended its children from a boy that was tormenting them in 1457. Wolves were routinely tortured to death in Christian rituals, and there is at least one known case of a horse being crucified upside down as possessed after it accidentally threw its owner who died.
In New World and Asian colonies, non Christians were often enslaved and worked to death. Jesuits helped cut a swath through the human population of the Americas north and south with the Word and contagion they carried with them. And contrary to Thanksgiving mythology, the Pilgrims were no friends to the indigenous population who were deemed subhuman even when they became Christians. And as slaves were brought from Africa by Christian slavers, hundreds of thousands were baptized by their evangelical Christian masters yet still raped, tortured, murdered, and worked to death indiscriminately by them.
So yeah, Jesus seems like he might have been a genuinely nice, educated, liberal rabbi who attempted to deconstruct some of the Old Testament's severity, but make no mistake, he has absolutely nothing to do with with the shitshow that came after him. To paraphrase Freddy N., 'The last Christian died on the cross.'