My memory is nearly gone, but I remember two things, that I am a great sinner, and that Christ is a great Saviour.
John Newton
Author of Amazing Grace
I love this quote because it summaries the whole of Christianity. That is, know who you are and know who God is. Some people stop with the sinner part ("Oh, I'm so awful") and miss the fact that the Gospel is really "good news". We should dwell on the Savior part yet never forget the sinner part. As someone once said, salvation is a two-sided coin, an attitude toward sin (repentance) and an attitude toward God (faith). As we turn the coin (turn away from sin) we face it in God's direction. It makes all the difference in the world whether you are looking at your own failures.. or looking at God's triumph.