I studied anthropology in college, and one of the things I learned was that certain human social structures always reappear. They can't be eliminated from society. One of those structures is religion. Today it is said we live in a secular society in which many people---the best people, the most enlightened people---do not believe in any religion. But I think that you cannot eliminate religion from the psyche of mankind. If you suppress it in one form, it merely re-emerges in another form. You can not believe in God, but you still have to believe in something that gives meaning to your life, and shapes your sense of the world. Such a belief is religious.
-- Michael Crichton, Environmentalism as Religion
In responding to a comment on the Gamers With Jobs forum regarding religion, I realized I had encapsulated an important feeling I might as well capture here, so here it is. If it seems a bit disjointed, that's because I was responding to various assertions made by another person:
For me, I certainly find any degree of time spent on religious readings/contemplation/church attendance/ceremony to be an unproductive waste of time, but I think for the typical "rub shoulders with God on Sunday" person they perceive a direct benefit from the time and energy spent, not unlike what one might get out of meditation (and probably for a similar reason, brain science-wise).
Being someone very jealous of my time (I need as much time as possible available to waste on games!), I observe the Islamic five-times-a-day prayer process with shock and horror. If the alternative is a fiery pit, I think I'll go for the alternative. Pretty much the same just for going to church on Sundays. But I'm sure many who participate in that get a direct brain-warmth hit both from taking time out to focus on something beyond themselves and from the knowledge that a billion+ other people are doing the same at the same time.
I don't believe the personal choice to practice religion is destined to result in subjugation of others, though in cases where it does lead to that, I think it's fair for the presumed subjugatees to fight back and fight back hard. It's an area where the normally cowardly me could see laying my life on the line.
I do suspect that the devotion time required for the devout Muslim may actually impact their society at large -- with so much time spent at prayer/mosque, can the society really compete when it comes to generating wealth and improving the standing of everyone? But that's just idle speculation for me; I have no idea how productive such people actually are.
Ultimately, I doubt that casual practice of religion is harmful. If the hypothesis that non-religious people tend to replace religion with woo-woo scientific and spiritual beliefs is true (and anecdotally, it sure seems true), it may well be the case that casual religion is actually less harmful than the alternative.