It’s easy to point out the problems that religion causes in this modern age (violence, intolerance, willful ignorance). Obviously, because religion has been around so long, it must have been beneficial to some degree in the past, otherwise religion as a whole would have gone “extinct” due to competition from non-religious societies. Daniel Dennett has already investigated religion with exactly this in mind in his book Breaking the Spell, and so I won’t go into why religion came about here, since I have nothing to add to Dennett’s comprehensive study. Instead I will investigate the benefits of religion in the modern world (or at least the benefits religion is supposed to have).
One positive effect of religion is that it answers the “big questions” for people, and thus gives them some kind of confidence or peace of mind (or so it is claimed). I don’t know exactly what these “big questions” are supposed to be. Possibly we are talking about morality, which I will address that below. The only other “big question” that I can think of is concerns about the nature of the afterlife (or lack thereof). But it is hard for me to believe that religion really provides people with a deeply satisfying answer to this question. For one thing most religions hold that there is a possibility for eternal punishment, which would seem to make people more uncertain about the afterlife rather than less. But let us assume for the moment that the religious have absolute confidence that they personally will not be punished in the afterlife, and thus that their beliefs are really giving them some extra peace of mind. If this is the case then why do the religious act as cautiously as the non-religious? If you really believed that as soon as you died you would get to go to the best place imaginable then I would think that you would be more willing to take risks that could lead to your early demise. Maybe you wouldn’t take foolish risks, but perhaps you would be more willing to take selfless risks, such as helping the poor in high crime areas, helping the citizens of nations suffering from natural disasters and violence, volunteering for the armed forces when a just war is being fought (I’ll let you decide for yourself if our current war is a just one), ect. Some of the religious certainly do take these risks, but the majority don’t, and this leads me to suspect that, consciously or unconsciously, they worry as much as the non-religious about death.
Another commonly claimed beneficial effect of religion is that it encourages people to act ethically. However, there is good reason to believe that people’s behavior (ethically) is independent of religious belief. For one the religious simply don’t behave much better than the non-religious in general, there are heroes and villains from both groups, meaning that if religion has an impact on ethical behavior it is a small one. Secondly there are reasons to be ethical even in the absence of religion, meaning that without religion people aren’t left in a moral vacuum. And finally the greatest impact on people’s behavior seems to be the role models that they model their behavior on when they are young, and this is completely independent of religion.
This brings me to the last possible benefit of religion in the modern age (or at least the last benefit that I have heard claimed), which is that religious belief makes some people feel better. This I think comes in two forms. One is that some people feel reassured by the idea that there is a personal god looking out for them, and I think this form is fairly harmless. The second form, however, is less benign. Some people use religion to give themselves a kind of absolute moral confidence. If they want to do something most of us would consider unethical they can find something in their religious books to support it, and thus can act on that desire without feeling ashamed of themselves. Certainly they feel better as a result of such confidence (wouldn’t you feel good if you believed that you were always doing the right thing, which just happens to coincide with exactly how you want to behave), but it is certainly bad for the rest of us. Now as to whether religion is justifiable because of the happiness it provides to some people (of the harmless variety), well I don’t think it is. There is a lot of baggage that comes with believing in religion, and there are many other ways to be happy and satisfied with ones life. If worse came to worse you could always take mild antidepressants.