The role of works in Catholicism is a very basic fundamentalist/Evangelical concern, the answer to which should be in every Catholic’s apologetics toolkit.
At least once in your life, you’re bound to come across a Protestant who states that we Catholics believe we are saved by works. In all likelihood, this person will defend the error by exclaiming heatedly, “Hey, I used to be a Catholic!” Or, if she’s a cradle Protestant, she’ll appeal to the authority of Cindy Lou Apostate or Reverend Expriest over at the First Church of the Intolerant Master, and if they don’t know what Catholics really believe ….
Before you start, you should make clear how you’re using certain terms. The most important term to clarify is “works” itself, but I’ll save that for later. Right now, here are some basic concepts:
- Concupiscence: The human tendency to sin, the legacy of original sin (CCC 1264, 1426, 2515).
- Faith: The individual’s personal adherence to God and free assent to the whole truth that God has revealed (CCC 26, 142, 150, 1814).
- Justification: The gracious action of God which frees us from sin and communicates “the righteousness of God through Jesus Christ” (Rom 3:22) (CCC 1987-1989).
- Redemption: The price paid by Christ’s sacrifice on the Cross to free us from slavery to sin (CCC 571, 601; cf. 517, 1372).
- Salvation: The forgiveness of sins and restoration of friendship with God (CCC 169).
- Sanctification: The process of healing or “perfecting” our wounded nature, an action of God’s grace (CCC 1999).
The Catholic understanding of faith takes a little more explaining. Faith is more than a simple assertion that God exists and Jesus is Lord: to believe X is not necessarily to be fully committed to its truth. The act of faith is the full commitment, by which the Christian “marries” himself to God and His revealed truth; by investing himself completely and utterly, he opens himself to God’s sanctifying grace, which begins to free him from slavery to sin made possible by concupiscence and to restore him to friendship with God.
So in the Catholic understanding of salvation economy, faith is the necessary first step to justification, which goes hand in hand with sanctification. The act of faith is a gift of God’s grace; however, it’s also a human act. It can be lost by any number of causes, especially if the person asserts his will in contradiction to God; it can be strong or weak. But it can also be regained through re-conversion; for this reason, we speak of salvation as a lifelong process rather than “once saved, always saved” (an argument for another time).
Faith, then, actively engages the person with God. Rote compliance with the Law of Moses doesn’t; it’s possible for a Jew to be orthodox in his observance of the Law and agnostic in his personal beliefs, because observance of the Law is a cultural requirement as much as a religious requirement.
Saint Paul chiefly refers to works in the sense of “observance of the Law”; works, in this sense, is short for “works of the law” (Rom 9:32; Gal 2:16, 3:2-10). For him, the ultimate symbol of reliance on the Law is circumcision:
Now I, Paul, say to you that if you receive circumcision, Christ will be of no advantage to you. I testify again to every man who receives circumcision that he is bound to keep the whole law. You are severed from Christ, you who would be justified by the law; you have fallen away from grace. For through the Spirit, by faith, we wait for the hope of righteousness. For in Christ Jesus neither circumcision nor uncircumcision is of any avail, but faith working through love (Gal 5:2-6 RSV).
In the bolded words we see a change in the meaning of “work”, and we now see the source of the difficulty. For St. Paul uses “works” in two senses, one to express compliance with the law, and the other to express the action of faith.
In this second sense, “works” are not irrelevant to the Christian life; rather, they’re the expression of faith made physical in the avoidance of evil and the doing of good. Far from having no impact on our eternal destiny, St. Paul makes it clear that God will judge us according to our deeds:
But by your hard and impenitent heart you are storing up wrath for yourself on the day of wrath when God's righteous judgment will be revealed. For he will render to every man according to his works: to those who by patience in well-doing seek for glory and honor and immortality, he will give eternal life; but for those who are factious and do not obey the truth, but obey wickedness, there will be wrath and fury (Rom 2:5-8 RSV).
“For we are his workmanship, created in Christ Jesus for good works, which God prepared beforehand, that we should walk in them” (Eph 2:10). God’s grace is given to us not just to cover over our sinfulness but to release us from sin’s power, so that we may “put off the old man that … is corrupt through deceitful lusts” and “put on the new man, created in the likeness of God in true righteousness and holiness” (Eph 4:22, 24).
So while faith opens us up to God’s grace, that grace not only justifies but sanctifies as well, and springs out into acts of justice, mercy and charity. Works are faith in action.
Jesus tells us, “Either make the tree good, and its fruit good; or make the tree bad, and its fruit bad; for the tree is known by its fruit” (Mt 12:33; cf. Lk 6:44). And again, “Not every one who says to me, ‘Lord, Lord,’ shall enter the kingdom of heaven, but he who does the will of my Father who is in heaven” (Mt 7:21; cf. Lk 6:45-46). Committing to Christ means giving everything we’ve got, holding nothing back for ourselves, “walking the talk” even if it means walking to the gallows for his sake.
Catechism of the Catholic Church I:3:1, §§ 142-165 (here, here and here) on the full nature of faith
Mt 19:16-17, Jn 14:21 on keeping Jesus' commandments
Jas 2:14-26—faith without works is dead; man saved by (faith and) works and not faith alone
Church Fathers on works and merit (courtesy Catholic Answers)