Evolutionary Idealism and Creationist Materialism

Hello guys, I have been struggling with this section - You only die twice/The Last Judgement - for a while. Zizek claims that Benjamin has touched the real nerve of the Stalinist symbolic edifice. I understand the idea that Zizek is criticizing here; the evolutionary - not atheist enough - understanding that Stalinism (and at times some Darwinists) have towards history, remaining idealist in the sense that it maintains a figure of the Big Other which "legitimizes" progress. However, I can't seem to grasp its counterpart: Creationist Materialism. Thank You!