That religion gave us some wonderful cultural or personal goodies is no argument for religion being true, or even useful. Without religion we would still come up with whatever our psyche demands because our psyche demands it. People are people.
One example is meditation. It was developed in Buddhism, migrated around the world, and now can be completely divorced from the religion that developed it.
I have used it at points in my life and I find it very calming and focusing. Awhile ago I ran into
this article in the L.A. Times about meditation led by a former Buddhist nun. The local museum here offers it unguided except for downloadable tracks to help you destress at the end of the week.
I'm an art lover, and I can get into a trance state at a concert or at a museum just from the art. I can also meditate without tibetan chimes or an mp3 over earbuds. This makes me think that meditation and the resulting feelings could have come about without religion, but without neuroscience people wouldn't understand their illusory mental state.
Neurologists have managed to study the effect of meditation (.pdf) on the brain. Functional magnetic resonance imaging (fMRI) shows the brain in action, and studies have shown that meditation affects many parts of the brain. Occam's razor would suggest that meditation is "all in the mind," and not at all supernatural. I've heard the argument that neurological phenomena that have been interpreted as religious experience are evidence that God has made the human mind such that he can dial in, when the human has made his/her brain receptive of course. But the same people who make this argument also believe that babies with undeveloped brains, brain-dead people, and people with severe brain damage have souls. How conveeeenient. So the soul is in the brain when it's having a religious experience, but it's also in the brain when it's incapable of having a religious experience.
So... religion may have invented meditation, or at least developed it, but it's all-natural and would probably have been discovered at some point anyway. We discovered mind-altering drugs all over the world. We would have discovered mind-altering practices, too. Not to mention, it's possible to have a mental state that
feels divine in many different cultures, with many different deities messing with the brain. If there were one true deity, wouldn't everyone have the same interpretation of their weird neurological states?
And speaking of art, if not for religion, would we have Bach's
B Minor Mass? What about the
Sistene Chapel?
Because I'm an art and music lover, this has been lobbed at me by believers more often than any other "argument." Or perhaps "jabbed" would be the better word, since it is usually said with an implied "Touché." I try very hard not to sigh before I point out that Bach also composed the Brandenburg concertos and the Mona Lisa is not a religious painting (not by Michelangelo, but still... )
In the past, artists did not have the artistic freedom that they do now. Michelangelo and Bach had employers, and they had specific job duties. In some eras, artists worked on commission, but they didn't have a free hand then, either. They were the best of their generations, so they had employers or patrons with the means to give them a broad canvas so the products were pretty spectacular. Michelangelo had many "canvases" and Bach had fine singers and instrumentalists to work with. But Michelangelo didn't have the freedom to paint pagan stories at the Vatican and Bach couldn't tamper with the words of the Mass. So the argument falls apart because of patronage. You can turn it around and say something like this: "Without the greediness of The Church, the best artists of Western Europe would have had the freedom to execute their own vision rather pander in religious sentiment."
The ultimate utility of religion is social control, especially supposed control of supposed morality. This one gets trotted out often in the letters to the editor in the local paper, and probably all over the country. A favorite version is: "Since they took God out of the schools there's been a decline in morality and society's going to hell in a handbasket." Not to mention, Newtown happened because God was expelled. There are a lot of problems with this, but foremost is that there are two Biblical moralities: in the Old Testament, God punishes the whole species, or a whole country, or a whole city, based on what only some people are doing. This terrifies the "good" people who think the rest of us are going to get them into trouble with their brutish sky daddy. In the New Testament, morality is a total mess, because salvation is based not on works, but on belief, but the main idea is forgiveness. Except in old-fashioned Catholicism, anything can be forgiven, including murder (but not butt-sex!)
There is something to the idea that religion influences morality, but not as much as believers think. First, not hurting other people is something you learn as a child in your family and then extend to your fellow humans in wider and wider circles. Whether you learn not to hit other kids in school, Sunday school, or the soccerfield, you still learn that lesson. Likewise, if your family is messed up or you have some brain malfunction and you turn out to be a sociopath, it doesn't matter if you go to church. A church-going sociopath has a ready-made pool of gullible suckers to take advantage of, and the unchurched sociopath has to make mayhem somewhere else.
Fear of the wrath of the invisible sky-daddy does seem to help some people stay on the "right" side, but only because their beliefs in the supernatural have been a crutch preventing them from developing their natural moral muscle. Those in the middle, a.k.a. those the Devil and God are battling for, will be influenced by whatever social force is most important to them, regardless of their religion.
So.... does the utility of a religion make any difference in whether it should be followed? If you think that atheists should join a church even though they don't believe in any of the tenets, then maybe yes (though I strongly disagree on that point) But if you think that the utility of religion is some kind of proof that atheists
should believe in that religion, then the answer is NO! It's just proof that money, power, and human evolution can sometimes result in something useful. It's not proof of the supernatural.