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

Its Instrument

"Being justified freely by His grace" (Romans 3:24); "being now justified by His blood" (Romans 5:9); "being now justified by faith" (Romans 5:1). A full exposition of the doctrine of justification requires that each of these propositions should be interpreted in their Scriptural sense, and that they be combined together in their true relations as to form one harmonious whole. Unless these three propositions be carefully distinguished there is sure to be confusion; unless all the three are steadily borne in mind we are sure to land in error. Each must be given its due weight, yet none must be understood in such a way as to make its force annul that of the others. Nor is this by any means a simple task, in fact none but a real teacher (that is, a spiritual theologian) who has devoted a lifetime to the undivided study of Scriptures is qualified for it. "The righteousness of God which is by faith of Jesus Christ" (Romans 3:22); "A man is justified by faith without the deeds of the law" (Romans 3:28); "even we have believed in Jesus Christ, that we might be justified by the faith of Christ, and not by the works of the law" (Galatians 2:16). What is the precise place and influence which faith has in the important affairs of justification? What is the exact nature or character of justifying faith? In what particular sense are we to understand this proposition that we are "justified by faith"? and what is the connection between that proposition and the postulates that we are "justified by grace" and "justified by Christ's blood"? These are matters which call for the utmost care. The nature of justifying faith requires to be closely defined so that its particular agency is correctly viewed, for it is easy to make a mistake here to the prejudice of Christ's honor and glory, which must not be given to another—no, not to faith itself. Many would-be teachers have erred at this point, for the common tendency of human nature is to arrogate to itself the glory which belongs alone to God. While there have been those who rejected the unscriptural notion that we can be justified before God by our own works, yet not a few of these very men virtually make a Savior of their own faith. Not only have some spoken of faith as though it were a contribution which God requires the sinner to make toward his own salvation—the last mite which was necessary to make up the price of his redemption; but others (who sneered at theologians and boasted of their superior understanding of the things of God) have insisted that faith itself is what constitutes us righteous before God, He regarding faith as righteousness. A deplorable example of what we have just mentioned is to be found in the comments made upon Romans 4 by Mr. J.N. Darby, the father of the Plymouth Brethren: "This was Abraham's faith. He believed the promise that he should be the father of many nations, because God had spoken, counting on the power of God, thus glorifying Him, without calling in question anything that He had said by looking at circumstances; therefore this also was counted to him for righteousness. He glorified God according to what God was. Now this was not written for his sake alone: the same faith shall be imputed to us also for righteousness" ("Synopsis" vol. 4, p. 133—italics ours). The Christ-dishonoring error contained in those statements will be exposed later on in this chapter. "How does faith justify a sinner in the sight of God? Answer: Faith justifies a sinner in the sight of God, not because of those other graces which do always accompany it, nor of good works that are the fruits of it, nor as if the grace of faith, or any act thereof, were imputed to him for justification; but only as it is an instrument by which he receives and applies Christ and His righteousness" (Westminster Confession of Faith). Though this definition was framed upwards of two hundred and fifty years ago, it is far superior to almost anything found in current literature on the subject. It is more accurate to speak of faith as the "instrument" rather than as the condition, for a "condition" is generally used to signify that for the sake whereof a benefit is conferred. Faith is neither the ground nor the substance of our justification, but simply the hand which receives the divine gift offered to us in the gospel. What is the precise place and influence which faith has in the important affair of justification? Romanist answer, It justifies us formally, not relatively: that is, upon the account of its own intrinsic value. They point out that faith is never alone, but "works by love" (Gal 5:6), and therefore its own excellency merits acceptance at God's hand. But the faith of the best is weak and deficient (Luke 17:5), and so could never satisfy the law, which requires a flawless perfection. If righteousness was given as a reward for faith, its possessor would have cause for boasting, expressly contrary to the apostle in Romans 3:26, 27. Moreover, such a method of justification would entirely frustrate the life and death of Christ, making His great sacrifice unnecessary. It is not faith as a spiritual grace which justifies us, but as an instrument—the hand which lays hold of Christ. In connection with justification, faith is not to be considered as a virtuous exercise of the heart, nor as a principle of holy obedience: "Because faith, as concerned in our justification, does not regard Christ as King, enacting laws, requiring obedience, and subduing depravity; but as a Substitute, answering the requirements of the divine law, and as a Priest expiating sin by His own death on the cross. Hence, in justification we read of 'precious faith... through the righteousness of God and our Savior Jesus Christ' (2 Peter 1:1) and of 'faith in His blood' (Romans 3:25), and believers are described as 'receiving the atonement' and 'receiving the gift of righteousness' (Romans 5:11, 17). Therefore it is evident that faith is represented as having an immediate regard to the vicarious work of Christ, and that it is considered not under the notion of exercising virtue or of performing a duty, but of receiving a free gift" (A. Booth). What is the relation of faith to justification? The Arminian answer to the question, refined somewhat by the Plymouth Brethren, is, that the act of believing is imputed to us for righteousness. One error leads to another. Mr. Darby denied that Gentiles were ever under the law, hence he denied also that Christ obeyed the law in His people's stead, and therefore as Christ's vicarious obedience is not reckoned to their account, he had to seek elsewhere for their righteousness. This he claimed to find in the Christian's own faith, insisting that their act of believing is imputed to them "for righteousness." To give his theory respectability, he clothed it in the language of several expressions found in Romans 4, though he knew quite well that the Greek afforded no foundation whatever for that which he built upon it. In Romans 4 we read "his faith is counted for righteousness" (verse 5), "faith was reckoned to Abraham for righteousness" (verse 9), "it was imputed to him for righteousness" (verse 22). Now in each of these verses the Greek preposition is "His" which never means "in the stead of," but always signifies "towards, in order to, with a view to": it has the uniform force of "unto." Its exact meaning and force is unequivocally plain in Romans 10:10, "with the heart man believes unto ("His") righteousness": that is, the believing heart reaches out toward and lays hold of Christ Himself. "This passage (Romans 10:10) may help us to understand what justification by faith is, for it shows that righteousness there comes to us when we embrace God's goodness offered to us in the gospel. We are then, for this reason, made just: because we believe that God is propitious to us through Christ" (J. Calvin). The Holy Spirit has used the Greek prepositions with unerring precision. Never do we find Him employing "His" in connection with Christ's satisfaction and sacrifice in our room and stead, but only "anti" or "huper," which means in lieu of. On the other hand, "anti" and "huper" are never used in connection with our believing, for faith is not accepted by God in lieu of perfect obedience. Faith must either be the ground of our acceptance with God, or the means or instrument of our becoming interested in the true meritorious ground, namely, the righteousness of Christ; it cannot stand in both relations to our justification. "God justifies, not by imputing faith itself, the act of believing, but by imputing the obedience and satisfaction of Christ" (Westminster Catechism). That faith itself cannot be the substance or ground of our justification is clear from many considerations. The "righteousness of God (that is, the satisfaction which Christ rendered to the law) is revealed to faith" (Romans 1:17) and so cannot be faith itself. Romans 10:10 declares "with the heart man believes unto righteousness" so that righteousness must be a distinct thing from believing. In Jeremiah 23:6 we read "The LORD our righteousness," so faith cannot be our righteousness. Let not Christ be dethroned in order to exalt faith: set not the servant above the master. "We acknowledge no righteousness but what the obedience and satisfaction of Christ yields us: His blood, not our faith; His satisfaction, not our believing it, is the matter of justification before God" (J. Flavel). What alterations are there in our faith! what minglings of unbelief at all times! Is this a foundation to build our justification and hope upon? Perhaps some will say, Are not the words of Scripture expressly on Mr. Darby's side? Does not Romans 4:5 affirm "faith is counted for righteousness"? We answer, Is the sense of Scripture on his side? Suppose I should undertake to prove that David was cleansed from guilt by the "hyssop" which grows on the wall: that would sound ridiculous. Yes; nevertheless, I should have the express words of Scripture to support me: "Purge me with hyssop, and I shall be clean" (Psalm 51:7). Yet clear as those words read, they would not afford me the least countenance imaginable from the sense and spirit of God's Word. Has the hyssop—a worthless shrub—any kind of fitness to stand in the stead of the sacrificial blood, and make an atonement for sin? No more fitness has faith to stand in the stead of Christ's perfect obedience, to act as our justifying righteousness, or procure our acceptance with God! An apology is really due many of our readers, for wasting their time with such puerilities, but we ask them to kindly bear with us. We hope it may please God to use this chapter to expose one of Mr. Darby's many grievous errors. For "grievous" this error most certainly is. His teaching that the Christian's faith, instead of the vicarious obedience of Christ, is reckoned for righteousness (Mr. W. Kelly, his chief lieutenant, wrote "his [Abraham's] faith in God's word as that which he exercised and which was accounted as righteousness"—see chapter 5) makes God guilty of a downright lie, for it represents Him as giving to faith a fictitious value—the believer has no righteousness, so God regards his poor faith as "righteousness." "And he believed in the LORD; and He counted it to him for righteousness" (Genesis 15:6). The one point to be decided here is: was it Abraham's faith itself which was in God's account taken for righteousness (horrible idea!), or, was it the righteousness of God in Christ which Abraham's faith prospectively laid hold of? The comments of the apostle in Romans 4:18-22 settle the point decisively. In these verses Paul emphasizes the natural impossibilities which stood in the way of God's promise of a numerous offspring to Abraham being fulfilled (the genital deadness both of his own body and Sarah's), and on the implicit confidence he had (notwithstanding the difficulties) in the power and faithfulness of God that He would perform what He promised. Hence, when the apostle adds, "Therefore it was imputed to him for righteousness" (verse 22), that "therefore" can only mean: Because through faith he completely lost sight of nature and self, and realized with undoubting assurance the sufficiency of the divine arm, and the certainty of its working. Abraham's faith, dear reader, was nothing more and nothing else than the renunciation of all virtue and strength in himself, and a hanging in childlike trust upon God for what He was able and willing to do. Far, very far, indeed, was his faith from being a mere substitute for a "righteousness" which he lacked. Far, very far was God from accepting his faith in lieu of a perfect obedience to His law. Rather was Abraham's faith the acting of a soul which found its life, its hope, its all in the Lord Himself. And that is what justifying faith is: it is "simply the instrument by which Christ and His righteousness are received in order to justification. It is emptiness filled with Christ's fullness; impotency lying down upon Christ's strength" (J.L. Girardeau). "The best obedience of my hands Dares not appear before Your throne; But faith can answer Your demands, By pleading what my Lord has done." What is the relation of faith to justification? Antinomians and hyper-Calvinists answer, Merely that of comfort or assurance. Their theory is that the elect were actually justified by God before the foundation of the world, and all that faith does now is to make this manifest in their conscience. This error was advocated by such men as W. Gadsby, J. Irons, James Wells, J.C. Philpot. That it originated not with these men is clear from the fact that the Puritans refuted it in their day. "By faith alone we obtain and receive the forgiveness of sins; for notwithstanding any antecedent act of God concerning us in and for Christ, we do not actually receive a complete soul-freeing discharge until we believe" (J. Owen). "It is vain to say I am justified only in respect to the court of mine own conscience. The faith that Paul and the other apostles were justified by, was their believing on Christ that they might be justified (Galatians 2:15, 16), and not a believing they were justified already; and therefore it was not an act of assurance" (T. Goodwin, vol. 8). How are we justified by faith? Having given a threefold negative answer: not by faith as a joint cause with works (Romanists), not by faith as an act of grace in us (Arminians), not by faith as it receives the Spirit's witness (Antinomians); we now turn to the positive answer. Faith justifies only as an instrument which God has appointed to the apprehension and application of Christ's righteousness. When we say that faith is the "instrument" of our justification, let it be clearly understood that we do not mean faith is the instrument with which God justifies, but the instrument whereby we receive Christ. Christ has merited righteousness for us, and faith in Christ is that which renders it meet in God's sight the purchased blessing be assigned. Faith unites to Christ, and being united to Him we are possessed of all that is in Christ, so far as is consistent with our capacity of receiving and God's appointment in giving. Having been made one with Christ in spirit, God now considers us as one with Him in law. We are justified by faith, and not for faith; not because of what faith is, but because of what it receives. "It has no efficacy of itself, but as it is the band of our union with Christ. The whole virtue of cleansing proceeds from Christ the object. We receive the water with our hands, but the cleansing virtue is not in our hands, but in the water, yet the water cannot cleanse us without our receiving it; our receiving it unites the water to us, and is a means whereby we are cleansed. And therefore is it observed that our justification by faith is always expressed in the passive, not in the active: we are justified by faith, not that faith justifies us. The efficacy is in Christ's blood; the reception of it is in our faith" (S. Charnock). Scripture knows no such thing as a justified unbeliever. There is nothing meritorious about believing, yet it is necessary in order to justification. It is not only the righteousness of Christ as imputed which justifies, but also as received (Romans 5:11, 17). The righteousness of Christ is not mine until I accept it as the Father's gift. "The believing sinner is 'justified by faith' only instrumentally, as he 'lives by eating' only instrumentally. Eating is the particular act by which he receives and appropriates food. Strictly speaking, he lives by bread alone, not by eating, or the act of masticating. And, strictly speaking, the sinner is justified by Christ's sacrifice alone, not by his act of believing in it" (W. Shedd). In the application of justification faith is not a builder, but a beholder; not an agent, but an instrument; it has nothing to do, but all to believe; nothing to give, but all to receive. God has not selected faith to be the instrument of justification because there is some peculiar virtue in faith, but rather because there is no merit in it: faith is self-emptying—"Therefore it is of faith that it might be by grace" (Romans 4:16). A gift is seen to be a gift when nothing is required or accepted of the recipient, but simply that he receive it. Whatever other properties faith may possess, it is simply as receiving Christ that it justifies. Were we said to be justified by repentance, by love, or by any other spiritual grace, it would convey the idea of something good in us being the consideration on which the blessing was bestowed; but justification by faith (correctly understood) conveys no such idea. "Faith justifies in no other way than as it introduces us into a participation of the righteousness of Christ" (J. Calvin). Justifying faith is a looking away from self, a renouncing of my own righteousness, a laying hold of Christ. Justifying faith consists, first, of a knowledge and belief of the truth revealed in Scripture thereon; second, in an abandonment of all pretense, claim or confidence in our own righteousness; third, in a trust in and reliance upon the righteousness of Christ, laying hold of the blessing which He purchased for us. It is the heart's approval and approbation of the method of justification proposed in the gospel: by Christ alone, proceeding from the pure grace of God, and excluding all human merits. "In the LORD have I righteousness and strength" (Isaiah 45:24). None will experimentally appreciate the righteousness of Christ until they have been experimentally stripped by the Spirit. Not until the Lord puts us in the fire and burns off our filthy rags, and makes us stand naked before Him, trembling from head to foot as we view the sword of His justice suspended over our heads, will any truly value "the best robe." Not until the condemning sentence of the law has been applied by the Spirit to the conscience does the guilty soul cry, "Lost, lost!" (Romans 7:9, 10). Not until there is a personal apprehension of the requirements of God's law, a feeling sense of our total inability to perform its righteous demands, and an honest realization that God would be just in banishing us from His presence forever, is the necessity for a precious Christ perceived by the soul.