In his own words: Keller on the Gospel and humility
Since I'm using his framework so much, I'll let him speak in his own words from a recent Christianity Today article (he does his own argument much more justice that I do):
"Humility is a byproduct of belief in the gospel of Christ. In the gospel, we have a confidence not based in our performance but in the love of God in Christ (Rom. 3:22-24). This frees us from having to always be looking at ourselves. Our sin was so great, nothing less than the death of Jesus could save us. He had to die for us. But his love for us was so great, Jesus was glad to die for us."
Read the full article.