Faith in Jesus + faith in nothing else = salvation.
If this is what is meant by sola fide, or what the proponents of it are trying to say, then they need to do a better job of explaining it. Christ Jesus and Christ Jesus alone is our hope of salvation. Just because faith and works (works of faith, or faith in action) always work together, and must work together, does not mean we have faith in our works. In fact, not only should we not have faith in our works, but we should also not have faith in our faith. Our faith must be in Christ Jesus alone and what He accomplished at Calvary. Having faith in our faith will not save us, just as having faith in our works will not save us. Neither faith in our faith or faith in our works justifies us.
Reformer John Calvin understood "that good works are always connected with faith," just as Puritan John Owen understood that "Obedient faith is that which saves." Commentator Simon J. Kistemaker understood that "Faith and action, then, are never separated. The one flows naturally from the other. Deeds originate in faith and faith supports the believer in his work." As I have been saying this entire time, faith and works must work in tandem.
Matthew Henry commented, "You see then (v. 24) how that by works a man is justified (comes into such a state of favour and friendship with God), and not by faith only; not by a bare opinion, or profession, or believing without obeying, but by having such a faith as is productive of good works." He continues, "Those works which evidence true faith must to works of self-denial, and such as God himself commands (as Abraham's offering up his son, his only son, was), and not such works as are pleasing to flesh and blood and may serve our interest, or are the mere fruits of our own imagination and devising." He further explains, "The actings of faith make it grow perfect, as the truth of faith makes it act."
Matthew Poole commented, "Ye see then; an inference either from the instance of Abraham, or from the whole preceding discourse. How that by works; works of new obedience. A man is justified; declared to be righteous, or approved as such, and acquitted from the guilt of hypocrisy. And not by faith only; not by a mere profession of faith, or a bare assent to the truth, without the fruit of good works." He continues, "Whereas James having to do with carnal professors, and such as abused the doctrine of grace to encourage themselves in sin, and thought it sufficient that they had faith, (such as it was,) though they did not live like believers, resting in an empty profession, with the neglect of holiness; his design plainly is, to show the effects and fruits of justification, viz. holiness and good works; thereby to check the vanity and folly of them who did thus divorce faith from a holy life, (which God hath joined to it,) and fancied themselves safe in the profession of the one, without any respect to, or care of, the other, as appears in this chapter, ver. 14, 17, 26."
What James is addressing is works that demonstrate and prove genuine faith, whereas what Paul is addressing is works of the Law, having faith that adherence to the Law will somehow justify you. Confused Christians who fail to pay attention to the context miss this and then attempt to lump all works together. Their favourite verse to use is Romans 3:28: "For we maintain that a man is justified by faith apart from works of the Law." The italicized part is usually what they try to emphasize. The underlined part is what they miss entirely every time. As I have pointed out before, the Law did not exist at the time of Abraham. It did not come about until approximately 300 years later. Rahab being a Gentile woman, what would the Law have meant to her? Nothing. The people who reject evidences of genuine faith (such as repentance or obedient faith) in support of a vain profession of faith are usually the same people who equate holy living and commands of holiness with legalism.
Martin Luther hated the book of James and thought it should not be part of the Bible. Sola fide was his expression, and it is no wonder. Obviously he, too, missed the difference between what Paul was addressing and what James was addressing. The definition of sola fide as meaning "we are justified by faith alone apart from the need for works" is false. James clearly teaches contrary to this, as does every instance of faith found in Scripture. Faith and faith in action always appear in tandem. Define sola fide as "we are justified by faith in Christ Jesus alone apart from faith in anything else" and it will be entirely true. But as it stands and has stood throughout history, I must reject it, as any true student of the Word who desires to conform themselves to the truth of Scripture will do, because it is entirely contrary to the Word of God: "You see that a man is justified...not by faith alone."
Getting Deeper Theologically
By the way, we are not saved by faith. "For by grace you have been saved." How? "Through faith." Faith is the instrument through which God chooses to orchestrate salvation, but salvation is entirely by grace, considering the fact that God "chose us in [Christ Jesus] before the foundation of the world." What state did my faith exist before the foundation of the world? Something to think about.