I don't know what the hell "down to Muslims" is supposed to mean, but all the nations that have ever existed, religions, cults, and ideologies all put together, do not even come close to the 270 million people killed by Islamist madmen for 1400 years. This stands as the one incomparable worst atrocity of world history. Islamic jihad.
I think if you added up everyone killed by a Christian in the last 1400 years it would beat the Muslims hands down.
Your thought is worse than wrong. It's preposterous. The most people, by far, wrongly killed by Christians, in the name of Christianity was in the Spanish Inquisition. This was perhaps over 90% of them. They numbered barely more than 150,000. The Muslim number is 1,800 times higher. If we examined the differences over the past 30 years, the number would be much higher than 1800 times more Muslim killings. It would be a million to one.