Justified by Faith Alone, but not a Faith that is Alone

I was listening to a debate on justification between a Reformed Protestant and Roman Catholic, and in the course of the debate the question was asked what an often repeated Reformed phrase - "men are saved (justified) by faith alone, but not a faith that is alone" - actually means. The Roman Catholic was having some problems understanding how this statement is compatible with the doctrine of sola fide (justification by faith alone).

Protestants believe [saving] faith is that alone which accesses us to Christ by whom we are justified (declared righteous). This is why it is called the instrumental cause of justification. When a Protestant says faith alone justifies, then, does he mean men don't need grace? No, because grace is rather the efficient cause of justification insofar as it alone produces, for instance, the faith within an individual by which he is instrumentally justified. Similarly, when a Protestant says Christ alone justifies, does he mean men don't need grace or faith? Again, no, because Christ is rather the sole ground of justification, i.e. He by whom the righteousness is merited according to which God declares the believer righteous. These "solas" all refer to different functions of one event: justification.

Now, when the Protestant says faith alone justifies, but not a faith that is alone, one must distinguish between the function of the faith and the nature of the faith. The function of the faith has already been explained: it accesses men to Christ. It consummates union to Him such that the believer may be said to be in Him and He in the believer. Faith alone is how one has recourse to the ground of justification.

But what is this faith? What is the nature of this saving faith which is alone that by which we are [instrumentally] justified? Is it a mere profession? Is it simply understanding the gospel? No. It is understanding and assent to or, equivalently, belief in the gospel. Why is this important?

As was pointed out, the reason anyone understands and assents to the gospel is by grace alone, the efficient cause of faith and, in turn, justification. By God's grace one receives a new nature in regeneration which causes justificatory belief in Christ (Romans 8:7-9, 1 John 5:1). But moreover, this new nature will, subsequent to belief and justification, incline one to practice righteousness (1 John 2:29-3:9). Both saving faith and good works follow from grace (Ephesians 2:8-10). One can't produce good works without a new nature, and one can't come to Christ without a new nature. Or, at least, so says the Reformed Protestant. Expressing the Reformed motto logically is simple. For example:

1. If you have saving faith, then you will do good works.
2. You do not do good works.
3. Therefore, you do not have saving faith.

Or:

1. If one has saving faith, he will have received it immediately upon being given a new nature.
2. If one has been given a new nature, he will yield good fruit.
3. If one has saving faith, he will yield good fruit.

The main point is good works don't justify in any sense. They merely serve as indicators or evidences to men. What do they indicate to men? Whether or not one who professes to have saving faith actually has saving faith or if they are just lying. Whether or not one possesses that faith alone by which men are instrumentally justified correlates with whether or not he does the good works which follow from a faith which justifies.

It may be asked what if one does not show forth good fruit because he is backsliding. Of course, since works don't save, a temporary absence of them does not automatically mean one isn't saved. What it does mean is that another who has not seen a person's good works has no reason to think the person has saving faith. Nevertheless, a new nature "naturally" (!) yields good works, so such backsliding should not be or remain the case if one truly believes in Christ.

There is always room for nuance. If a person dies immediately after believing so that no one can have seen him do a good work, he will be saved. If I have just introduced myself to you and you identify yourself as a Christian, it may take some time for me to evaluate your profession of faith. Etc. The above syllogisms, therefore, may be restated for the practical benefit of men:

1. If you have saving faith, then you will do good works.
2. I have not seen you do good works.
3. Therefore, I have no reason to suppose you have saving faith [other than, perhaps, your own profession].