“The righteousness of God which is by faith of Jesus Christ” (Rom. 3:22); “A man is justified by faith without the deeds of the law” (Rom. 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” (Gal. 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 His 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 honour and glory, which must not be given to another—no, not to faith itself.
...We are justified by faith, and not for faith; not because of what faith is, but because of what it receives. “It hath 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 (Rom. 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. -A.W. Pink