This post is not orginial to me but rather was just posted on the DG blog (found here). I simply found it good enough to repost...
What is a distinguishing mark of a believer? At our 2009 Pastors Conference Mark Dever gave us a helpful and memorable word:
"The difference between a Christian and non-Christian: When a non-Christian is convicted of sin, he sides with his sin. When a Christian is convicted of sin, he sides with God, against himself."