O foolish Galatians, who hath bewitched you, that ye should not obey the truth, before whose eyes Jesus Christ hath been evidently set forth, crucified among you? This only would I learn of you, Received ye the Spirit by the works of the law, or by the hearing of faith? Are ye so foolish? having begun in the Spirit, are ye now made perfect by the flesh? (Galatians 3:1-3)
Not long after many of the Galatians believed in Jesus Christ, many of them reverted back to attempting to please God through good deeds and obedience to the law.
We cannot do one thing to improve on our righteous standing with God. Jesus Christ has once and for all satisfied the just and holy demands of God.
As we bask in this unmerited favor, let us be constrained by gracefulness and love to serve Him.