We explain and express the need for authentic community in church in myriad ways. Nearly all of the answers we come up with to answer "Why community?" are valid and true. But nearly all of them, like so many of our purposes these days, are slightly off the mark.
The point of community should not be to feel connected or to experience connectedness, nor should it be to cooperate in making the church "work." Those (and more) are valid reasons for and results of real community, but they still do not get at the primary reason for believers doing discipleship in community.
I think the absolute best work on church may be a little book on Christian fellowship by Dietrich Bonhoeffer called Life Together. In that book, Bonhoeffer writes:
God has willed that we should seek and find His living Word in the witness of a brother, in the mouth of man. Therefore, the Christian needs another Christian who speaks God's Word to him. He needs him again and again when he becomes uncertain and discouraged, for by himself he cannot help himself without belying the truth. He needs his brother man as a bearer and proclaimer of the divine word of salvation. He needs his brother solely because of Jesus Christ. The Christ in his own heart is weaker than the Christ in the word of his brother; his own heart is uncertain, his brother's is sure.
And that also clarifies the goal of all Christian community: they meet one another as bringers of the message of salvation.
See, the Gospel is so much bigger, and fuller, than just "getting saved." It is an ongoing need and comfort for Christians at every stage of the journey. I need the good news every day, for as long as I am living I will need faith in Jesus. The goal of Christian community, then, as a proclaimer and bearer of the Gospel, is to proclaim it to each other and bear it to each other, as well as to seekers.
Christian community is really a "me third" project. When we come together to worship and fellowship, we are reflecting in image and actualizing in practice the beauty of the Gospel -- that Jesus Christ has come to reconcile sinners to God and to each other. Community, at its most authentic, actualizes the Great Commandment(s). You remember the Commandment, right? "Love the Lord your God with all your heart, soul, mind, and strength. And love your neighbor as yourself." So when we gather to worship together and to follow Jesus in discipleship together, we are creating a Great Commandment community, which is really the best sort of community a church can hope for.
Love for God, love for others. Reconciliation with God, reconciliation with others. That is the aim of Christian community, and it must be the primary focus, else community becomes about function (pragmatism) or feelings (self idolatry). We do not participate in and foster community to get something out of it or even to "do our part" for the church, but we do get something out of it and the church is built by our contribution as a result when we participate in and foster community to see God glorified and the message of salvation reflected in our fellowship.
Elsewhere in Life Together, Bonhoeffer writes:
We are torn out of our own existence and set down in the midst of the holy history of God on earth. There God dealt with us, and there He still deals with us, our needs and our sins, in judgment and grace. It is not that God is the spectator and sharer of our present life, howsoever important that is; but rather that we are the reverent listeners and participants in God's action in the sacred story, the history of the Christ on earth. And only in so far as we are there, is God with us today also.
As a writer, I love, love, love the idea of Story as it relates to the work God is doing in the world. (I've explored this idea in an "old" Thinklings post titled The Call to Discipleship: An Invitation to the Story.) When we think of our Christian life and all that it entails as God's Story, we get a better sense of where we are headed and what our motivations are to be. If our sense of the Christian life is limited to our story, we have automatically missed the mark of a Great Commandment, "me third" Christian life.
It is God's story, and we are characters in it. We find our place, accept our roles, and make our mark on the world, not for our sake or for our glory, but for the Gospel's sake and for God's glory. I like the whole "be free to dream" thing, but it does seem to gloss over that it is God's dream we are set free to realize, not necessarily ours. We don't need more evangelical entrepreneurs in the church, pioneers of the new church culture hoping to craft communities around their innovations and Big Ideas. We need more disciples willing to crucify their flesh and get into the bigger, grander, more radical, more "dreamy" Story of the Gospel of Jesus Christ. And that is the why of community. Because it glorifies God and because it unites Jesus with sinners, of whom this "mature" Christian is the worst.