Religion is the prefect template for corruption. Anywhere from hundreds to millions of devout worshipers who believe the unfounded teachings of a human (either in book form or spoken word) and are typically willing to die for those beliefs has all the makings of disaster.
And I agree, this applies to governments and corporations as well. Pretty much anything that exploits an ideal.
As I stated above, I recently read How Religion Poisons Everything as well. No idea if you've read this book yourself, but it has some very compelling arguments as to the evil nature contained within religion.
Putting faith and believing in the creative works of human beings, using those beliefs to start wars, shun homosexuals, commit acts of horror and atrocity.
And this doesn't just come from "large hierarchies". Have you considered the religious suicide cults of the world? Even on a small scale, group think through the template of religion can be very deadly.
There is nothing at all obvious about the claim that this is an evil caused by religion, rather than a problem with consolidated power.