The only good reason to practice any religion is because you believe that it's true. However, I'm strongly of the opinion that religion-- or Christianity, at least, though I imagine all these points apply to other religions, at least to some extent-- has many benefits for society and for individuals that do not rest upon its truth or falsehood. I will make a list.
1) The existence of a clergy. A clergy is an educated, cultured, intellectual class that brings benefit to an entire society by their very existence. Their bread and butter is spiritual things; they don't have to devote their best mental efforts to marketing yoghurt or assessing insurance claims or anything else so limiting. They are spectators (and actors) in the drama of human life in a way that few other people, even doctors and firefighters and social workers, could claim to be. Think of the extent to which scholarship, especially in Ireland, has been indebted to priests. There is a Medieval Studies library (really, just a room) in the library where I work; I had never actually gone into it in thirteen years of working in the library, since it's so seldom used. But when I did get to go inside, I was interested to see a series of portraits of the medieval library's previous librarians; I think there were three, and they were all Catholic priests. This was very common in Ireland until recently. Priests were at the forefront of most social, cultural and sporting initiatives.
Priests often fill roles which would otherwise go unfilled. I was reading recently about the man who lived in an airport terminal for a great part of his life, the man on whom the Tom Hanks movie was based. It said that he frequently (several times a week) had visits from the airport priest. Who else would do that?
2) The practice of ritual and ceremony. Any group of people can design and institute a ceremony or a ritual for any purpose whatsoever. But so few do. It's embarrassing. It seems arbitrary. It's hard to get people to go along with it. And yet I think human nature craves ritual and ceremony.
The rituals and ceremonies of the Church, and indeed of most organized religions, are so venerable, and so much an accepted part of the social landscape, that they don't suffer from these problems. And I really feel that the performance of such rituals and ceremonies enriches everybody, not just those who participate in them. They are part of the spectacle of existence.
3) The differentiation of sex roles. I believe that one of the profound cravings of human nature-- so profound, that in many people it is actually sub-conscious-- is the desire to celebrate sexual difference, to exult in one's masculinity or femininity. You'll notice this if you ever see a group of people heading out for a formal event-- the women in flowing gowns and carrying flowers, the men in elegant suits and ties and self-conciously opening doors for their ladies, and giving them their arms. Isn't there a sense of liberation about this, a sense of freedom from the strait-jacket of unisex sameness? I always get the impression that people in this situation are not playing a role, but rather stepping out of a role and able to breathe more freely.
Religion tends to give different roles to at least some men and women based on their sex. In the Catholic religion, a woman can't become a priest, and a man can't become a nun. I'm intrigued to see how many young Catholic women wear head-coverings in church. And the kind of women who I see wearing head-coverings in church don't seem at all like cowed, oppressed, submissive women. They seem like very self-confident and self-possessed women making a statement.
4) The survival of folk-lore. A practiced religion brings with it a huge body of hymns, prayers, stories, devotions, traditions, and so forth. Where else do you get this, in today's world?
5) The existence of churches, places upon which money and attention are lavished but which have no 'practical' use. Where else do you get this, either?
6) The sense of historical continuity. I always feel a thrill when I hear someone with a strong Dublin accent reading a Scripture reading from the Old Testament, from the world of ancient Israel, and I reflect how that tradition has survived in an unbroken line through the centuries. The thrill is hearing it read out, not as a historical curiosity, but as a matter of the highest contemporary relevance.
7) Too many others to mention.