I think that this has been done a bit in Great Debates before, usually in reference to the idea that religion has killed more people than anything else. The problem I see with this idea is that it’s hard to tie a direct connection between religion and a murderous outcome. I would say that most things that claim religion as the cause can also equally claim a desire for power, wealth, or land as well. Can you define your question a bit more?
The problems you run into here may be illustrated by the Taiping rebellion which killed around 20 million people. Would you mark that down as Christian?
I very much doubt that anything like a factual answer to this question is possible, for a number of reasons, including[ul]
[li]the difficulty of defining “religion” or distinguishing what counts as religion for the purposes of a question like this[/li][li]the difficulty in determining a killer’s (or perpetrator of violence’s) true motivation or cause[/li][li]the fact that things like wars and persecutions have complex, multiple factors causing them[/li][/ul]
Right. Take the situation in Northern Ireland. “The Troubles” are ostensably a religious conflict, but in reality it’s an ethnically-based fight for political dominance: the native Irish people versus the British/Scottish latecomers.