The effectiveness of enforcement mechanisms is testable. I've seen nothing to suggest that outsourcing punishment to invisible sky wizards is an effective mechanism relative to alternatives. ...That statement must sound really strange out of context. The initial results are irrelevant, you have to look at a larger timescale to get at what matters. People will make mistakes and societies will act sub-optimally, this a given unless you assume society is already utopian. The difference between religion and reason is that reason can over time correct itself, while religion can't. While its theoretically possible that reason's attempts to correct itself are as likely to make things worse as better, that is a grim outlook that is basically declaring reason to be unusable due to human limitations. Its results have been sub-optimal. It may have been useful early on in human history when we didn't have the tools developed society has, but now its just a liability. Viruses are dependent on the cells of organisms for survival. Viruses do nothing but kill cells, the very thing they are dependent on for survival. Yet despite that, viruses haven't been competed out. Religion is a self-perpetuating meme. While it is more benign than your average virus, things like "kill people who would be host to other ideology" and "think irrationally whenever someone attacks this ideology, but otherwise act rationally" are still two of many actions that are to the benefit of the religious ideology advocating them and to the detriment of mankind.