The story goes that on one occasion, the French general Napoleon sentenced a young soldier to prison for being a deserter; his mother, sadly shocked, begged the great statesman to have compassion and let him go free. Napoleon replied, "He does not deserve it!". But the woman insisted; it is precisely because he is not worthy of your favor that I ask you to pardon him. And immediately, the feared general gave the order to release him.

Grace is unearned favor, because one does not have the ability to attain it, much less repay it.

Ephesians 2:8-9 NKJV

8 For by grace you have been saved through faith, and that not of yourselves; it is the gift of God, 9 not of works, lest anyone should boast.

Romans 5:8 NKJV

8 But God demonstrates His own love toward us, in that while we were still sinners, Christ died for us.