I'd argue that the surviving religions are more like the strongest viruses of the mind, not really the most useful mutations for society. You could look at the progress of societies and religions as the co-evolution of hosts and parasites, rather than of a single species acquiring useful new features :)
I'd say the truth is somewhere in between. Religions were a useful adaption. But after being supplanted by more useful mind viruses (like philosophy, which is itself becoming outdated; or formal justice systems), then their utility no longer mattered - just their ability to cling on.
That depends very much on how easy it is to find new hosts.
From Wikipedia: The book presents the Sumerian language as the firmware programming language for the brainstem, which is supposedly functioning as the BIOS for the human brain. According to characters in the book, the goddess Asherah is the personification of a linguistic virus, similar to a computer virus. The god Enki created a counter-program which he called a nam-shub that caused all of humanity to speak different languages as a protection against Asherah (a re-interpretation of the ancient Near Eastern story of the Tower of Babel).