“And behold, a certain lawyer stood up and put Him to the test, saying, ‘Teacher, what shall I do to inherit eternal life?’ 26 And He said to him, ‘What is written in the Law? How does it read to you?’ 27 And he answered and said, ‘You shall love the Lord your God will all your heart, and with all your soul, and with all your strength, and all your mind; and your neighbor as yourself.’ 28 And He said to him, ‘You have answered correctly; do this, and you will live.'” (Luke 10:25-28).

Notice that the lawyer was testing Jesus (v. 25) and asked what works he must do to have eternal life.  The lawyer obviously had faith in God that produced good works consistent with the Law since he quoted the Law to Jesus when Jesus asked him what was written in the Law.  Jesus commends him on his answer about loving God and loving one’s neighbor and then follows up with the story of the Good Samaritan (Luke 10:30-37) to show that works of love are the fulfillment of Loving Your Neighbor.  This is why Jesus said, “Do this and you will live.”

Jesus was pointing the Lawyer to the law and requiring it of him.  It was the standard with which he judged himself.  If a Roman Catholic asked Jesus what he should do to inherit eternal life, perhaps Jesus would have answered in like manner, according to the standard of the Catholic and according to the standards of Catholicism which says that keeping the 10 commandments is necessary for salvation.

• “The authority of the Magisterium extends also to the specific precepts of the natural law because their observance, demanded by the Creator, is necessary for salvation. In recalling the prescriptions of the natural law, the Magist
  erium of the Church exercises an essential part of its prophetic office of proclaiming to men what they truly are and reminding them of what they should be before God,” (CCC 2036).
• “The Council of Trent teaches that the Ten Commandments are obligatory for Christians and that the justified man is still bound to keep them; the Second Vatican Council confirms: “The bishops, successors of the apostles, receive from the Lord . . . the mission of teaching all peoples, and of preaching the Gospel to every creature, so that all men may attain salvation through faith, Baptism and the observance of the Commandments,” (CCC 2068).

Keep the Law and you’ll be saved, but can you do that?  If you stumble in one part, you’re guilty of all (James 2:10).  It follows that if keeping it saves you, then not keeping it will damn you.  So, if you fail to keep it at all, you are cursed (Gal. 3:10).  If you go to confession to confess your sins, then you have failed to keep that Law and are damned. This is why justification is

by faith alone in Christ’s work alone, and that explains why Paul said in Romans 3:28 that we are “justified by faith apart from the works of the law” because no one is able to keep the law perfectly.

Jesus applies peoples’ own standards to themselves when they seek to be justified before God.  If you hold to justification by faith alone, then the standard is not works but faith in Christ’s work.  If your standard is faith and works, then you’re obligated to keep the Law.  However, such a standard can save no one.  This is why we need the gospel that tells us Jesus kept the Law perfectly (1 Pet. 2:22) and that we can be justified before God by faith in Him (Romans 4:3, 5; 5:1; John 1:12; 3:16) without the works of the Law (Romans 3:28).