Marxists everywhere.
Leftism is fundamentally driven by envy, which is itself a side-effect of vanity. Envy seeks to destroy perceived advantages enjoyed by competitors rather than adopt them. Religion is obviously a competitive advantage. Many of its benefits can be scientifically verified and are beyond dispute. Depending on the task at hand some religions offer far superior benefits than others. The modern form of Judaism is optimized for prospering while being greatly outnumbered. Buddhism is great for high population density living where there is a higher need for getting along. Despite its many other advantages, Christianity has proven to be the best religion for winning in a world consumed by war. In a fox hole during battle you'd want a Christian beside you.