I saw a funny commercial on TV. A young boy stood near home plate and shouted, “I’m the greatest hitter in the world!” He tossed a baseball into the air, swung mightily, and missed. “Strike one,” he said to himself. He shouted louder, “I’m the greatest hitter in the world!” flipped a ball into the air, swung, and missed. “Strike two.” More determined than ever, he spat into his hands, turned his cap around, and shouted defiantly, “I’m the greatest hitter in the world!” threw the ball into the air, and struck himself out. I was feeling sorry for the little guy, when, in a flash of recognition for what he had accomplished, he exclaimed, “I’m the greatest pitcher in the world!”

The ad was about the power of optimism, and it’s funny because the kid seemed more delusional than anything. We wonder what it would take to convince the boy that he wasn’t the greatest at something. And just as he overestimated his ability, so we tend to inflate our efforts. We need to hear Isaiah’s reminder that our best deeds before God are “nothing but filthy rags” (Isaiah 64:6).

Martin Luther and John Calvin caught Isaiah’s point and taught that we have never done a completely good deed, for even our best efforts are marred by impure motives. They said that we need a double justification. Our person must be justified by the blood of Jesus, and our works are only accepted when God forgives our sins by His grace.

This strong sense of depravity is no cause for despair, for even though we never become perfect in this life, we can still make progress. And all the credit goes to God. As John Newton wrote in his memoir, “I remember two things very clearly: I’m a great sinner, and Christ is a great Savior.”