Søren Kierkegaard had a beef with Christianity. One way to describe that beef is to say that Christianity had become domesticated. It wasn't serious enough for his pietism. It was too bourgeois. In brief, it was too much a matter of form and not enough of substance. Much of the body of his writing was dedicated to these criticisms. There is merit to his criticisms.
It isn't uncommon to hear similar complaints today: Christianity has become too institutional, and institutions excuse people from their need for individual faith; organized religions are not supple enough to respond to contemporary issues and, so, cannot avoid being not only conservative but hidebound; perhaps because they are unavoidably conservative, organized religions tend to teach the ruling ideology rather than the radical truths on which they were originally founded, so they end up on the side of the oppressor rather than the oppressed.
Those who make this contemporary criticism often share a version of Edmond de Goncourt's attitude toward religion. He is said to have remarked, "If there is a God, atheism must seem to him less an insult than religion." Terry Eagleton is among the smartest of those who make these kinds of complaints (as in his very smart Reason, Faith, and Revolution: Reflections on the God Debate). There is merit to these criticisms too.
So what can I say in defense of organized religion if I believe that Kierkegaard and Eagleton each have a point?
Perhaps the most important thing to note is that, at least for Christianity (and surely for many other religions as well, though I speak only of what I know), religion is not a merely individual thing. Protestantism opened up the possibility of thinking of religion that way, though few Protestants (perhaps only Kierkegaard) understand religion purely in individual terms, as nothing more than the relation of the individual to God.
Christianity is a religion of relationship. As Jean-Yves Lacoste points out, religion is intersubjective. We pray. I say "Our Father" rather than "My Father," even if I am in the quiet of my closet. The words of a religious rite are our words before God, not merely mine. They not only place us before him, they situate us together.
A person who idly repeats the words of the prayers used for the Lord's Supper in LDS services is not doing what the priest does when he blesses the elements of that ritual. And the priest cannot bless them apart from his relation to the bishop and to the congregation. I cannot anoint myself with oil and give myself a blessing for the healing of the sick nor can I perform any other ordinance (rite) for myself. Acts of religious devotion are our acts, usually explicitly, sometimes only implicitly.
Religion is intersubjective because human existence is fundamentally intersubjective. I am not an individual first and then part of humanity. First I am with other people in the world, among them, one of them. Then, out of that intersubjectivity, I am constituted as an individual, I am separated from others and can, by an act of reflection, analyze my experience of the other person and come to know her as if she were a stranger, as someone unrelated to and apart from me.
I can make myself an object to myself; I can make another an object. There are many good reasons for doing so. But that ability is something derivative from the fact that I exist in the world inescapably with others.
Organized religion can go wrong in many ways. Kierkegaard and modern critics point them out. But organized religion enacts a fundamental truth: we are before God together rather than alone. Our life is at base a life of communion.
In spite of its ability to go wrong, when it goes right organized Christianity does two things: it brings us back to an experience of our communal existence—"Thou shalt love thy neighbor as thyself" (Mt. 22:39), and it places that communal existence before God, with whom we are also in communion: "Thou shalt love the Lord thy God with all thy heart" (Mt. 22:37).
Of course the danger is that our intersubjective life, our communion with one another before God, will become merely bourgeois and that what-we-do-together will become merely what-one-does. But the escape from that danger does not come by ridding ourselves of organized religion. We cannot throw out both baby and bath water. The escape from sin, individual or communal, doesn't come from rejecting our life together, but from new life together. It comes through repentance, turning about.
Those who are repelled by the sins of organized religion must find within it a life full of charity and absent accusation. They must repentantly draw us toward repentance.