I read this over on Richard Hall's "Connexions" weblog.  It's a post by Kim and it's a quote from Will Willimon, Bishop in the United Methodist Church and one of my former professors at Duke Divinity School.

I quote this here because I read it and could hear sermons that I've preached on sin over the years and phrases that have appeared in them.   In the church we are "learning how to be a sinner."  I've used Reinhold Neibuhr's comment that "the doctrine of original sin is the only empirically verifiable Christian doctrine" and also Barth's quote, "Only Christians sin."  In many sermons I've said, "Sin is a Christian construct.  It takes place in our understanding of our relationship with God.  It moves beyond offense to humanity or the earth or merely bad things to a theological point."

I think the section below, entirely quoted on Richard Hall's site, gets at some good stuff on sin.

Part of the prophetic ministry of the church is to teach people that we are sinners. Think of the church as lifelong learning in how to be a sinner….

Reinhold Niebuhr, citing Herbert Butterfield, is well known for his remark that the doctrine of original sin is the only empirically verifiable Christian doctrine. Even those who do not know that Jesus Christ is Lord, know sin. Niebuhr was wrong. Christian sin results not from our unhappiness with the limits of human existence and our inappropriate response to our discontented finitude (Niebuhr). Rather, Christian sin is derivative of and dependent upon what Christians know about God as revealed in Jesus Christ.

…. In all of his massive Church Dogmatics, [Karl] Barth did not get around to original sin until the very end. The traditional path had been to begin with the problem, our sin, and then to move to doctrines of redemption and atonement, God’s answer for our sin. Barth refused to take this path because if human beings are as sinful as Christian theology claims us to be, then even our attempts to admit our sin will be deceitful, sentimental, and self-serving. The “sins” of non-Christians are puny. We can only speak about sin after telling the story of our redemption.

As Barth says, “Only Christians sin.” That is, only Christians have inculcated the insights and the sets of practices that make sin comprehensible. Christians learn to sin, not by beginning with the allegedly universal observations about the “human condition,” but rather by beginning with a story of redemption. Only later are we able to move to an account of sin. The joyful story of our forgiveness precedes any honest telling of our sin….

William Willimon, Pastor: The Theology and Practice of Ordained Ministry (Nashville: Abingdon Press, 2002), pp. 270-72.