"Use it or lose it" is a vital principle for Christian living!
Question: Since eternal life is a free gift from God, through the Holy Spirit, what role do "good works" play in the life of a Christian?
Answer: We cannot, by our own "righteousness" and "good works," persuade God to grant us eternal life. Scripture reminds us: "But we are all like an unclean thing, and all our righteousnesses are like filthy rags; we all fade as a leaf, and our iniquities, like the wind, have taken us away" (Isaiah 64:6). We all need salvation, "for all have sinned and fall short of the glory of God" (Romans 3:23).
Those who may assume that they are fulfilling the letter of the law, and that doing so will earn them eternal life, should consider that they have not yet encountered every trial Satan can offer. Before his conversion, Saul thought he was perfectly obeying God. "If anyone else thinks he may have confidence in the flesh, I more so: circumcised the eighth day, of the stock of Israel, of the tribe of Benjamin, a Hebrew of the Hebrews; concerning the law, a Pharisee; concerning zeal, persecuting the church; concerning the righteousness which is in the law, blameless" (Philippians 3:3-6). Saul believed he was righteous in God's eyes, until the resurrected and glorified Christ stuck him down on the road to Damascus (Acts 9:1-4).
Yet the commandments do matter. When a wealthy young man asked Jesus, "what shall I do that I may inherit eternal life?" (Mark 10:17), Jesus Christ first rebuked him, saying that no one but God is truly "good." Then, Christ proceeded to remind him of the commandments of God" (vv. 18-19). When he asserted that he had kept the commandments faithfully, Christ told him he must sell whatever you have... and come, take up the cross, and follow Me" (v. 21) the rich young man "went away sorrowful" (v. 22). Jesus did not tell the young ruler that keeping the commandments did not matter. Rather, Christ demonstrated that by valuing worldly wealth more than the Kingdom of God, this young man was not doing the works God required of him!
It is through the Holy Spirit in us that we are saved. "But the Helper, the Holy Spirit... the Father will send in My name... will teach you all things, and bring to your remembrance all things that I said to you" (John 14:26). We receive the Holy Spirit after repentance and baptism: "Then Peter said to them, 'Repent, and let every one of you be baptized in the name of Jesus Christ for the remission of sins; and you shall receive the gift of the Holy Spirit. For the promise is to you and to your children, and to all who are afar off, as many as the Lord our God will call'" (Acts 2:38-39).
We are in the process of "being saved" (cf. 1 Corinthians 1:18; 2 Corinthians 2:15). Yet we must complete the process: "But he who endures to the end shall be saved" (Matthew 24:13).
It is a mistake to pit "faith" against "works." We read: "But someone will say, 'You have faith, and I have works.' Show me your faith without your works, and I will show you my faith by my works" (James 2:18). Yet neither our works, nor the Holy Spirit now within us, can guarantee salvation. God can even take the gift of the Holy Spirit back, if we intentionally reject it and decide to stop following the path of righteousness (Hebrews 6:4-6). Even ancient King David knew the importance of God's Spirit, and asked that God not take it from him (Psalm 51:11). We must be careful not to "quench" the Spirit that God has given us (1 Thessalonians 5:19).
One who actually believes in God and His promises will inevitably strive to obey His laws, and the indwelling Holy Spirit—an unmerited gift from God the Father—will help us become increasingly practiced at obeying those laws. As we obey, yielding to the Spirit, we will increasingly overcome our faults as we grow in grace and knowledge. We must use the gift of God's Spirit—the use of which will be manifest by our works—or we may lose it!