Only HN would compare religion to L2 regularization! That said, your perspective "self replicating cultural program that benefits its biological host" is one that I think I've seen expressed before by the philosopher/cogscientist Josha Bach, and it seemed to fit well. It's not just a cultural program, it's effectively is a "mind virus/symbiont" (depending on who you ask), in that it also modifies behavior and psychology.