Found this excellent excerpt from an article by John Ortberg over at Christianity Today.com
Sin damages my capacity for God. Sin blinds. The danger is not that God won't respond to my repeated repentance; the danger is that I might become so ensnared that I become simply unable or unwilling to repent. This is the dynamic at work when Paul says, "And God gave them over to a depraved mind."
The greatest sin would be to stop wrestling!