Even I wouldn't say "religion" causes all wars. A lot of them certainly. but all?. Faith perhaps, but faith isn't reserved exclusively for supernatural beliefs.
Honestly the reason I don't think that viewpoint is correct is because I feel it fails to understand the position religion takes in the lives of others and turns religion into almost a living entity in it of itself with an influence of its own.
Religion is more often the source of justification for what were more important causes.
In the same way I don't consider Religion the cause of the KKK, I consider Racism to be and religion to be the excuse/context they use for that racism.
A virus is not alive by itself, it is merely a bundle of genetic information wrapped in a shell of protein. Yet give it access to the cellular machinery of an appropriate host, and it displays all the qualities of a living thing. It consumes energy, alters its environment(host), competes with other infections, evolves to overcome its natural predators in the form of antibodies and white blood cells, reproduces to spread through its environment and from host to host. Even if it harms or kills a host, it can still spread through the larger population. And while a typical virus is something a population can withstand, it just takes one wrong mutation to bring a population to its knees.
A religion is not alive by itself, it is merely a bundle of memetic information wrapped in a shell of ritual. Yet give it access to the mental machinery of an appropriate host, and it displays all the qualities of a living thing. It consumes energy, alters its environment(host), competes with other religions, evolves to overcome its natural predators in the form of logic and reason, reproduces to spread through its environment and from host to host. Even if it harms or kills a host, it can still spread through the larger population. And while a typical religion is something a population can withstand, it just takes one wrong mutation to bring a population to its knees.
Religions are effectively memetic viruses, parasites of the human mind.