When Christians got power did they also not commit mass murders as with the Gunpowder Plot, the Pogroms of the 1930’s and before that with the Inquisitions (I and II) and before that with certain sects that were considered to be heretics, of which one of many (the Waldensians) were nearly annihilated by Catholics.
Some Catholics have used their faith to harass and massacre others, as have some Protestants, Muslims and others. For one to say that the Jewish people entering into the Promised Land was not followed by a wholesale massacre of the inhabitants in the land before they were would be to ignore history.
In the end, lack of faith in a religion does not necessarily mean violence will ensue, nor does someone “getting religion” necessarily mean that they will be all “love one another as I have loved you,” which Jesus admonished His followers to do.
What you said is true. And you need to add the sins of atheists, who when they had power, committed such mass murder and oppression that put everything before it to shame.
The truth is that man is fallen - no matter what he calls himself in the schemes of spiritual or non-spiritual things. Men ruling over men is not a pretty picture. There is none innocent. I think we agree that freedom for everyone - all at the same time - is the way to go.