Going by history id say Buddhism. No religions unblemished but Buddhism probably has the lowest kill count. Not Hinduism, or judaism bloods been spilt in there name a good bit. Islam and christianity have the bloodiest history and more killed in there name than all the others and at one point both advocated violence as a means of spreading so its definitely neither of them. I barely heard of jainisium so i cant say i no enough to comment on it.