"We sin by trying to overcome sin on our own."

But there is no way for us to crawl out of sin's hole. Indeed, the very attempt to crawl out on our own only sinks us in deeper. That may seem a strange claim. But if God is the source of all our good, then God must be the source of our freedom from sin. When we attempt to free ourselves on our own, we deny the true source of our goodness and wrong God by claiming for ourselves what is God's. We sin by trying to overcome sin on our own.

--Miroslav Volf, Free of Charge: Giving and Forgiving in a Culture Stripped of Grace (Grand Rapids, MI: Zondervan, 2005), 36-37.