The following is from The Doctrine of Justification by Arthur Pink:

Its Evidence

In Romans 3:28 the Apostle Paul declared "that a man is justified by faith without the deeds of the law," and then produces the case of Abraham to prove his assertion. But the Apostle James, from the case of the same Abraham, draws quite another conclusion, saying, "You see then how that by works a man is justified, and not by faith only" (James 2:24). This is one of the "contradictions in the Bible" to which infidels appeal in support of their unbelief. But the Christian, however difficult he finds it to harmonize passages apparently opposite, knows there cannot be any contradiction in the Word of God. Faith has unshaken confidence in the inerrancy of Holy Writ. Faith is humble too and prays, "That which I see not teach You me" (Job. 34:32). Nor is faith lazy; it prompts its possessor unto a reverent examination and diligent investigation of that which puzzles and perplexes, seeking to discover the subject of each separate book, the scope of each writer, the connections of each passage. Now the design of the Apostle Paul in Romans 3:28 may be clearly perceived from its context. He is treating of the great matter of a sinner's justification before God: he shows that it cannot be by works of the law, because by the law all men are condemned, and also because if men were justified on the ground of their own doings, then boasting could not be excluded. Positively he affirms that justification is by grace, through the redemption that is in Christ Jesus. His reasoning will appear the more conclusive if the whole passage (Romans 3:19-28) be read attentively. Because the Jews had a high regard of Abraham, the apostle proceeded to show in the 4th chapter of Romans that Abraham was justified in that very way—apart from any works of his own, by faith alone. By such a method of justification the pride of the creature is strained, and the grace of God is magnified.

Now the scope of the Apostle James is very different: his Epistle was written to counteract quite another error. Fallen men are creatures of extremes: no sooner are they driven out of the false refuge of trusting to their own righteousness, than they fly to the opposite and no less dangerous error of supposing that, since they cannot be justified by their own works, that there is no necessity whatever for good works, and no danger from ungodly living and unholy practice. It is very clear from the New Testament itself that very soon after the gospel was freely proclaimed, there arose many who turned the grace of God into "lasciviousness": that this was not only quickly espoused in theory, but soon had free course in practice. It was therefore the chief design of the Apostle James to show the great wickedness and awful danger of unholy practice and to assert the imperative necessity of good works. The Apostle James devoted much of his Epistle to the exposing of any empty profession. In his second chapter, particularly, he addresses himself unto those who rested in a notion which they called "faith," accounting an intellectual assent to the truth of the gospel sufficient for their salvation, though it had no spiritual influence upon their hearts, tempers, or conduct. The apostle shows their hope was a vain one, and that their "faith" was not a whit superior to that possessed by the demons.

From the example of Abraham he proves that justifying faith is a very different thing from the "faith" of empty professors, because it enabled him to perform the hardest and most painful act of obedience, even the offering up of his only son upon the altar; which act took place many years after he had been justified by God, and which act manifested the reality and nature of his faith. From what has been said above, it should be very evident that the "justification" of which Paul treats is entirely different from the "justification" with which James deals. The doctrine of the former is that nothing renders any sinner acceptable to God but faith in the Lord Jesus Christ; the doctrine of the latter is that such a faith is not solitary, but accompanied with every good work, and that where good works are absent, justifying faith cannot exist. James is insistent that it is not enough to say I have justifying faith, I must give proof of the same by exhibiting those fruits which love toward God and love toward men necessarily produce. Paul writes of our justification before God, James of our justification before men. Paul treats of the justification of persons; James, of the justification of our profession. The one is by faith alone; the other is by a faith which works by love and produces obedience. Now it is of first importance that the above-mentioned distinctions should be clearly grasped. When Christian theologians affirm that the sinner is justified by faith alone, they do not mean that faith exists alone in the person justified, for justifying faith is always accompanied by all the other graces which the Spirit imparts at our regeneration; nor do they mean that nothing else is required in order to our receiving forgiveness from God, for He requires repentance and conversion as well as faith (Acts 3:19). No, rather do they mean that there is nothing else in sinners themselves to which their justification is in Scripture ascribed: nothing else is required of them or exists in them which stands in the same relation to justification as their faith does, or which exerts any casual influence or any efficacy of instrumentality in producing the result of their being justified (Condensed from Cunningham).

On the other hand, that faith which justifies is not an idle and inoperative principle, but one that purifies the heart (Acts 15:9) and works by love (Galatians 5:6). It is faith which can easily be distinguished from that mental faith of the empty professor. It is this which the Apostle James insists so emphatically upon. The subject of this Epistle is not salvation by grace and justification by faith, but the testing of those who claim to have faith. His design is not to show the ground on which sinners are accepted before God, but to make known that which evidences a sinner's having been justified. He insists that the tree is known by its fruits, that a righteous person is one who walks in the paths of righteousness. He declares that the man who is not a doer of the Word, but a "hearer only," is self-deceived, deluded. When God justifies a man, He sanctifies him too: the two blessings are inseparable, never found apart. Unless the subject and scope of James' Epistle be clearly seen, the apprehension of many of its statements can only issue in God-dishonoring, grace-repudiating, soul-destroying error. To this portion of the Word of God, more than any other, have legalists appealed in their opposition to the grand truth of justification by grace, through faith, without works.

To the declarations of this Epistle have they turned to find support for their Christ-insulting, man-exalting, gospel-repudiating error of justification by human works. Merit-mongers of all descriptions cite James 2 for the purpose of setting aside all that is taught elsewhere in Scripture on the subject of justification. Romanists, and their half-brothers the Arminians, quote "You see then how that by works a man is justified, and not by faith only" (verse 24), and suppose that ends all argument. We propose now to take up James 2:14-26 and offer a few comments thereon. "What does it profit, my brethren, though a man say he has faith, and have not works? Can faith save him?" (verse 14). Observe carefully that the apostle does not here ask, "What does it profit a man though he has faith and have not works?"—such a supposition is nowhere countenanced by the Word of God: it were to suppose the impossibility for wherever real faith exists, good works necessarily follow. No, instead he asks, "What does it profit, my brethren, though a man (not "one of you"!) say he has faith"? Professing to be a Christian when a man is not one, may secure a standing among men, improve his moral and social prestige, obtain membership in a "church," and promote his commercial interests; but can it save his soul? It is not that those empty professors who call themselves Christians are all (though many probably are) conscious hypocrites, rather are they deceived souls, and the tragic thing is that in most places there is nothing in the preaching which is at all calculated to un-deceive them; instead, there is only that which bolsters them up in their delusion.

There is a large class in Christendom today who are satisfied with a bare profession. They have heard expounded some of the fundamentals of the Christian faith, and have given an intellectual assent thereto, and they mistake that for a saving knowledge of the Truth. Their minds are instructed, but their hearts are not reached, nor their lives transformed. They are still worldly in their affections and ways. There is no real subjection to God, no holiness of walk, no fruit to Christ's glory. Their "faith" is of no value at all; their profession is vain. "What does it profit, my brethren, though a man say he has faith, and have not works? Can faith save him?" By noting the emphasis upon the word "say," we perceive at once that James is arguing against those who substituted a theoretical belief of the gospel for the whole of evangelical religion, and who replied to all exhortations and reproofs by saying, "We are not justified by our works, but by faith alone." He therefore begins by asking what profit is there in professing to be a believer, when a man is devoid of true piety? The answer is, none whatever. To merely say I have faith when I am unable to appeal to any good works and spiritual fruits as the evidence of it, profits neither the speaker nor those who listen to his empty talk.

Ability to prate in an orthodox manner about the doctrines of Christianity is a vastly different thing from justifying faith. "If a brother or sister be naked, and destitute of daily food, And one of you say unto them, Depart in peace, be you warmed and filled; notwithstanding you give them not those things which are needful to the body; what does it profit?" (verses 15, 16). Here the apostle shows by an opposite illustration the utter worthlessness of fair talking which is unaccompanied by practical deeds: notice the "say unto them, depart in peace" etc. What is the use and value of feigning to be charitable when the works of charity are withheld? None whatever: empty bellies are not filled by benevolent words, nor are naked backs clothed by good wishes. Nor is the soul saved by a bare profession of the gospel. "Faith works by love" (Galatians 5:6). The first "fruit of the spirit," that is of the new nature in the regenerated soul, is "love" (Galatians 5:22). When faith has truly been wrought in the heart by the Holy Spirit, that faith is manifested in love—love toward God, love toward His commandments (John 14:23), love toward the brethren, love toward our fellow-creatures. Therefore in testing the "faith" of the empty professor, the apostle at once puts to the proof his love. In showing the pretense of his love, he proves the worthlessness of his "faith." "But whoever has this world's good, and sees his brother have need, and shuts up his affections of compassion from him, how dwells the love of God in him?" (1 John 3:17)! Genuine love is operative; so is genuine faith. "Even so faith, if it has not works, is dead, being alone" (James 2:17). Here the apostle applies the illustration he has employed to the case before him, proving the worthlessness of a lifeless and inoperative "faith." Even our fellow-men would promptly denounce as valueless a "love" which was gushing in words but lacking in works. Unregenerate people are not deceived by those who talk benignly to the indigent, but who refuse to minister unto their needs. And think you, my reader, that the omniscient God is to be imposed upon by an empty profession? Has He not said, "Why call you Me, Lord, Lord, and do not the things which I say?" (Luke 6:46). That "faith" which is only of the lips and is not confirmed by evidence in the life, is useless. No matter how clear and sound may be my head-knowledge of the Truth, no matter how good a talker upon divine things I am, if my walk is not controlled by the precepts of God, then I am but "sounding brass and a tinkling symbol." "Faith, if it has not works, is dead, being alone." It is not a living and fruitful faith, like the faith of God's elect, but a thing which is utterly worthless— "dead." It is "alone," that is, divorced from love to God and men and every holy affection. How could our holy Lord approve of such a "faith"! As works without faith are "dead" (Hebrews 9:14), so a "faith" which is without "works" is a dead one. "Yes, a man may 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).

Here the true Christian challenges the empty professor: You claim to be a believer, but disgrace the name of Christ by your worldly walk, so do not expect the real saints to regard you as a brother until you display your faith in the good works of a holy life. The emphatic word in this verse is "show"—proof is demanded: demonstrate your faith to be genuine. Actions speak louder than words: unless our profession can endure that test it is worthless. Only true holiness of heart and life vindicates a profession of being justified by faith. "You Believe that there is one God; you do well: the devils also believe, and tremble" (verse 19). Here the apostle anticipates an objection: I do actually believe in the Lord! Very well, so also do the demons, but what is the fruit of their "believing"? Does it influence their hearts and lives, does it transform their conduct Godward and manward? It does not. Then what is their "believing" worth! "But will you know, O vain man, that faith without works is dead?" (verse 20): "vain" signifies "empty," exposing the hollowness of one who claims to be justified by faith yet lacks the evidence of an obedient walk. "Was not Abraham our father justified by works, when he had offered Isaac his son upon the altar? See you how faith wrought with his works, and by works was faith made perfect?" (verses 21, 22). The faith which reposes on Christ is not an idle, but an active and fruitful principle. Abraham had been justified many years before (Genesis 15:6); the offering up of Isaac (Genesis 22) was the open attestation of his faith and the manifestation of the sincerity of his profession.

"By works was faith made perfect" means, in actual obedience it reaches its designed end, the purpose for which it was given is realized. "Made perfect" also signifies revealed or made known (see 2 Corinthians 10:9). "And the Scripture was fulfilled which says, Abraham believed God, and it was imputed unto him for righteousness: and he was called the Friend of God" (James 2:23). The "scripture" here is God's testimony to Abraham in Genesis 15:6: that testimony was "fulfilled" or verified when Abraham gave the supreme demonstration of his obedience to God. Our being informed here that Abraham was "called the Friend of God" is in beautiful accord with the tenor of the whole of this passage, as is clear from a comparison with John 15:14: "You are my friends, if you do whatever I command you." "You see then how that by works a man is justified, and not by faith only" (James 2:24). In the "you see then" the apostle draws his "conclusion" from the foregoing. It is by "works," by acts of implicit obedience to the divine command, such as Abraham exercised—and not by a mere "faith" of the brain and the lips—that we justify our profession of being believers, that we prove our right to be regarded as Christians. "Likewise also was not Rahab the harlot justified by works, when she had received the messengers, and had sent them out another way?" (verse 25). Why bring in the case of Rahab? Was not the example of Abraham conclusive and sufficient? First, because "two witnesses" are required for the truth to be "established"—cf. Romans 4:3, 6. Second, because, it might be objected Abraham's case was so exceptional that it could be no criterion to measure others by. Very well: Rahab was a poor Gentile, a heathen, a harlot; yet she too was justified by faith (Hebrews 11:31), and later demonstrated her faith by "works"—receiving the spies at the imminent risk of her own life. "For as the body without the spirit is dead, so faith without works is dead also" (James 2:26).

Here is the summing up: a breathless carcass and a worthless faith are alike useless as unto all the ends of natural and spiritual life. Thus the apostle has conclusively shown the worthlessness of the garb of orthodoxy when worn by lifeless professors. He has fully exposed the error of those who rest in a bare profession of the gospel—as if that could save them, when the temper of their minds and the tenor of their lives was diametrically opposed to the holy religion they professed. A holy heart and an obedient walk are the scriptural evidence of our having been justified by God.