I posted this in Amazon forum for God is Not Great under the pseudonym "God". Got good enough response there that I think I'll post it here too.
Religion is a preconceived set of beliefs (such as the Bible), that those who seek them try hard to modify to make them reasonable enough to adopt. This allows us to incorporate them with our other pre-existing beliefs to become part of our greater belief set.
However, religion is inherently opposed to changes of this kind, and it often includes warnings against changes in its adaptation. Also, the purveyors of the religion have already incorporated the religion into their own belief structure, and they want to ensure a new member to the religion does not modify the set in ways that differ from their own. And in the case where the individual decides to forgo incorporating the belief set, it's purveyors will recall the religion's warnings about punishment for those who consciously choose to reject it.
Religion has dogmatism at it's core. Open debate over all of it's proposals is discouraged. This is particularly true when those involved have already made a heavy personal investment in the religion and will defend it even when doing so goes against their own reasoning.
I would repeat that religion is not just something that a particular individual believes. It's a structure that is advanced as a whole from one group of individuals to others. There are people who consider themselves religious but abhor organized religion. To me, all religion is organized. Even if you don't go to the meetings. Because all religious descriptions always appear to include some group membership and a singular source for the religious edicts.