We Christians first gained worldly, secular power in the 4th century, when the Roman Emperor Constantine became a Christian. So, let's say that we've had some control over many secular governments for nearly 1700 years.

Let's also say (though it's a gross exaggeration, at best) that every war in Europe during that time was the fault of Christianity. The Crusades, the Thirty Years War, let's say that Christianity deserves the blame for everyone killed in every was since Cosnatntine became a Christian. Then we'll toss in the occasional withc hunt or Inquisition, and blame the resulting deaths on Christianity.

Boy, we've got a lot of dead people to answer for, don't we?

Now, to the best of my knowledge, the first official atheist government didn't exist until 1917, when Vladimir Ilyich Ulanov (aka Lenin) took over the Rusian empire. So, atheists have had secular power for just 97 years, right. That means... in just 97 measly years, atheists managed to kill waaaaay more people than all the Crusaders, Inquisitors and assorted Christian maniacs combined had managed to kill in 1700 years!

That doesn't mean atheists are more prone to killing than Christians are, or that they enjoy killing more than Christians do. But it's pretty obvious atheists are a lot BETTER at killing huge numbers of poeople than Christians are.