Now to the one who works, his wage is not credited as a favor, but as what is due. But to the one who does not work, but believes in Him who justifies the ungodly, his faith is credited as righteousness. Romans 4:4-5
A favorite “I Love Lucy” episode depicts “Lucy Ricardo” trying to box chocolates from a speeding conveyer belt. Many laborers do “piece work,” and are paid by the number of items they produce or process. They get their “due” based on their work. God’s righteousness is absolute and only 100 percent purity meets His “quota.” But God’s mercy is also absolute; therefore He makes provision to satisfy the requirements of His justice. You can’t do enough “piece work” to satisfy God’s expectations so He takes care of them for you through Jesus Christ. That’s the wonderful promise of His grace.