I don't remember anything about worshipping some ancient entites from my soviet past. It was mostly agnostic with some shift to the side of atheism, but this shift was mostly ignored by population that was after traditional Orthodox Christianity regardless of jewish attempts to force atheism.

As for death, switch to capitalism was as deadly, as wars. In USSR white population steadily grow, despite all communist shit, with capitalism white population on ex-USSR territory began to shrink.

So, speaking about death cult, I'll choose modern capitalism as a nominate. When population put profit above anything else, that does not help with producing life.