The Reformation doctrine of justification is frequently summed up in the slogan sola fide, which means “by faith alone.” The phrase sola fide stands for the teaching that justification is by faith alone.
The Roman Catholic Church, historically, has also taught that justification is by faith. They say that faith is the initial stage of justification. It is the foundation and root of our justification. Rome insists on the necessity of faith for justification. So the fide in sola fide is clearly affirmed by Rome. What is not affirmed by Rome is the sola, because even though faith is the initiation, the foundation, and the root of justification, its mere presence is not enough to effect justification. There must be something besides faith in order for us to be justified—a necessary condition. A necessary condition is something that must be present in order for an effect or consequence to follow, but its presence does not guarantee the result.
For example, under normal circumstances, a necessary condition for fire is the presence of oxygen. But, fortunately for us, the mere presence of oxygen is not enough to cause a fire. If it were, we would catch on fire every time we took a breath of air. So we distinguish between a necessary condition and a sufficient condition. A sufficient condition absolutely guarantees that the result will follow.
Given that distinction, we can see the difference between the Roman Catholic view and the Reformation view of the relationship between faith and justification. In the Roman view, faith is a necessary condition for justification, not a sufficient condition for it. In the Protestant view, faith is not only a necessary condition but also a sufficient condition for justification. That is, when we put our faith and trust in Christ, God will most surely declare us justified in His sight. The Reformation view, which is the biblical view, is that if faith is present, justification is inevitably present as well.
What is unthinkable in the Reformation view is that we could have faith without justification. We cannot have justification without faith, and we cannot have faith without justification. Rome says that we cannot have justification without faith, but we can have faith without justification. We can keep our faith but commit a mortal sin that will destroy the grace of justification, so that we will be damned (without proper penance). But for the Reformers, the mere possession of genuine faith is all that is required in order for us to receive the grace and maintain the state of justification.
The confession says this:
Faith, thus receiving and resting on Christ and his righteousness, is the alone instrument of justification.
An instrument is a tool that is used for a particular purpose. When the framers of the Westminster Confession wrote that faith is the alone instrument of justification, they were aware of the sixteenth-century dispute regarding the instrumental cause of justification. It is necessary to have a clear understanding of this doctrine—the instrumental cause of justification—because it is about how we are saved.
The term instrumental cause goes back in history to the fourth century before Christ, to the philosophy of Aristotle. He was concerned to explain motion and change. In that process, he tried to isolate various causes that contribute to something’s change of state or status. How does that relate to our question here? We, by nature, are not justified. We are unjust, and our status before God is that we deserve his unmitigated wrath. We need a change of our status, from a state of damnation to a state of justification.
Aristotle distinguished four kinds of causes: the formal cause, the efficient cause, the final cause, and the material cause. He did not include the instrumental cause. His four causes, however, formed the basis for the idea of instrumental cause.
He used the illustration of a statue that starts out as a block of stone from the quarry. Aristotle defined the block of stone as the material cause, the stuff out of which something is made. The formal cause is the idea in the sculptor’s mind, or his blueprint or sketch, of the way that he wants the finished product to look. There has to be an idea before there can be a result. The efficient cause is that which brings about the change from stone to statue, and in this case it is the sculptor. He is the one who makes it happen. The final cause is the purpose for which the thing is made, which in this case may be to beautify a garden.
To these four causes, we may add the idea of the instrumental cause, which is the means by which the change takes place. If the sculptor wants to change the block of stone into a statue, he has to chip away at the stone to shape, form, and smooth it. His chisel and his hammer are the instruments, the means by which the change is wrought. In English, we often indicate means with the words by and through.
When the Reformers said that justification is by faith or through faith, they affirmed that the means or the instrument by which we are justified is faith and faith alone. The only instrument that we need, the only tool required to move us from a state of damnation to a state of justification is faith, but faith is not the only thing that we need in order to be justified. We also need Christ in order to be justified. That is, in order to be justified, we need His perfect righteousness and His atonement on the cross. Everything that is required by God to meet His standard of righteousness and justice has been fulfilled objectively in and through the work of Christ. He has done it all. The whole Roman Catholic–Protestant debate on justification is not over the objective work of Christ so much as it is over how we receive the benefits of His work. How is the objective work of Christ subjectively appropriated? The answer that the Reformers gave, based on the teaching of the Apostle Paul, was “in and through, or by and through, faith alone.” But it is not faith alone that saves us. When we say that justification is by faith alone, we are saying that justification is by and through our faith in Christ alone.
The instrumental cause of justification, according to Rome, is baptism and penance. Rome defines these sacraments as the instruments by and through which a person is justified. The difference is between salvation that is accomplished sacerdotally (that is, through the church’s administration of the sacraments) and salvation that is experienced through faith in Christ alone. This is all the difference in the world. The confession says that faith is the only instrument of justification because it is through faith alone that we rest on and receive the righteousness of Christ. The righteousness of Christ, the benefits of His atonement, the objective merit or grounds of our justification, are freely offered to anyone who believes. “The righteous shall live by faith” (Rom.1:17). We are justified not by faith plus works but by faith alone. All that is needed to enter the kingdom of God is faith or trust in the work of Christ alone.
Faith is not the grounds of our justification. The grounds of our justification is the righteousness of Christ, His merit. The Reformers said that the meritorious cause of our justification is the righteousness of Christ alone. The instrumental cause of our justification is faith, but when we say that we are justified by faith alone, we do not mean that faith is a meritorious work that adds anything to the ground of our justification.
What difference does that make practically? There are people who say they believe in justification by faith alone but who rely on their faith as if it were meritorious or a good work that will satisfy the demands of God’s justice. The fact that a person possesses faith adds no merit to his account. It adds infinite merit to his account by imputation, but it is the merit of Christ that is imputed to him. We can receive Christ’s merit only by faith, and there is no merit to that. The only One who can save us is Christ, and the only way we can get access to Him is through faith. We do not rest on anything else in our lives except Christ and His righteousness for our salvation.
This excerpt is adapted from Truths We Confess by R.C. Sproul. In Truths We Confess, now thoroughly revised and available in a single, accessible volume, Dr. Sproul introduces readers to this remarkable confession, explaining its insights and applying them to modern life. Order the hardcover book today.