Grace does not excuse sin. Grace teaches us how to overcome sin (Titus 2:12). Some have asked how grace teaches us, since we are no longer under law but under grace (Romans 6:14).
The simple answer is that grace came to reveal God’s love. Paul wrote to Titus,
In grace our Savior God appeared, to make his love for mankind clear. He came to save us – not by works of righteousness that we had done, but according to His mercy – through the washing of regeneration and renewal by the Holy Spirit. Titus 3:4-5
And John wrote,
And we have known and believed the love that God has for us. God is love; and he that dwells in love dwells in God, and God in him. 1 John 4:16
No one born of God makes a practice of sinning, for God’s seed abides in him, and he cannot keep on sinning because he has been born of God. 1 John 3:9
When we know and believe in God’s love for us, the grace that we receive because of this faith instructs, leads, and empowers us to overcome sin. When we were under the Law, we were required to overcome sin of our own efforts. The fault is not in the Law, but in those required to keep the Law.
But God found fault with the people and said: “The days are coming, declares the Lord, when I will make a new covenant with the people… It will not be like the covenant I made with their ancestors when I took them by the hand to lead them out of Egypt, because they did not remain faithful to my covenant… This is the covenant I will establish with the people of Israel after that time, declares the Lord. I will put my laws in their minds and write them on their hearts. I will be their God, and they will be my people. No longer will they teach their neighbor, or say to one another, ‘Know the Lord,’ because they will all know me, from the least of them to the greatest. For I will be merciful toward their iniquities, and I will remember their sins no more.” By calling this covenant “new,” he has made the first one obsolete; Hebrews 8:8-13
My friend, we have received a better covenant, the covenant of His grace. Believe in His love for you, and be transformed by the power of His grace!