The "New Atheists" have described religion as a delusion, a poison, and now apparently a virus. The author says at the end that he hoped people would view their religions differently, but I doubt many religionists could get past the title of this book: The Religion Virus: Why We Believe in God, An Evolutionist Explains Religion's Incredible Hold on Humanity.
Craig James applies Dawkins' theory of memes to the main concepts of religion. In many ways I found this convincing, but he tries a little too hard to force the meme concept onto the book.
Still, it's a powerful idea. It explains how God could be so contradictory, taking both sides of a football game for instance. It also explains how the various stories and phases of the Old Testament portray different concepts of God.
The memeplex lost me a bit, but I get the concept of multiple memes sticking together and supporting each other. I imagine a herd of gazellish ideas sticking together, which would be very adaptive.
Essentially, the analogy states that ideas that are advantageous to themselves will survive. The most obvious is missionary work, of course. Religions that prosletyze survive and those that don't, won't. Christianity & Islam prosletyze and they number in the billions. Judaism doesn't, and hence comprises a tiny minority in the world.
Some of the book oversimplifies, especially the virus analogy. Religion has helped or hurt its societies to varying degrees. Of course you can claim that there are beneficial parasites as well as destructive ones, and some that are only destructive under the right circumstances.
It's definitely a thought-provoking book. Anyone who has read the Bible knows that the "unchanging" God has changed quite a bit from the beginning to the end. Even the commandment "Thou shalt have no other gods before me" implies that at one time Judaism was not monotheistic. "The" God just wanted to be Numero Uno. The warrior god seems to have softened his approach. He wiped out the world, then he wiped out entire peoples or countries in genocidal rampages, then honed in on cities and eventually individuals. "An eye for an eye" was a big moral improvement over genocide. Then later there's no payment at all thanks to penal substitution. God went from destroying the whole world to saying "fuhgeddaboudit." This book frames a theory that explains these changes.