No, that crown of causer of the biggest holocausts humanity has ever witnessed goes to Christianity. And if you want to narrow it down, Britain, or rather, England, has got hundreds of millions on any other nation, even outdoing Spain, which is saying a HELL of a lot.
And if you want to narrow it down even further than that, especially in light of you bringing up economic models, then the English East India Company is the champ. Millions dead. For spices. Spices that today have still not been used for the world's most blandest food. Let that sink in. Hundreds of millions dead. For spices. And English food is about plain and simple and tasteless as food can get. What did they do with those spices, sell them to Spain and Portugal?
The East India Company wasn't Marxist, were it?
PS: God didn't build any Nation, unless you're talking about that deed he sold to Abraham back in the day. And even that wasn't exactly in perpetuity, as any Roman can tell you,,,