One of the books I’m reading is "John Calvin: A Pilgrim’s Life", and in it I just read a great sort of ”why grace changes everything" quote:

Namely, that we see God as the only lord of our soul, and His Law as the only rule and spiritual instruction for our conscience, so that we do not serve Him according to all kinds of foolish human regulations. Further that He wants to be served by us in spirit and with a clean heart. On the other hand, we admit that in us there is nothing but unrighteousness, that we are corrupt in all we think and do, so that our heart is an abyss of evil. We therefore doubt ourselves, deny any claim to our own wisdom, worthiness, or aptitude for the good, turn to the fountain of all good which is Jesus Christ, and receive what He gives us, the reward of His suffering and death, so that we may be reconciled to God through it. Washed clean in His blood, we are now no longer afraid that our sins will prevent us from finding grace at His heavenly throne. Assured that our sins have been freely forgiven on the basis of His sacrifice, we find our rest and assurance of salvation. We are sanctified through His Spirit to devote ourselves to obeying the justice of God. Strengthened by His grace, we will be victorious over the devil, the world, and the flesh. Finally, as members of His body, we do not doubt that God counts us among His children, and that we may with full confidence address Him as our Father.