The Protestant position on saving faith is that it is the instrument by which the sinner is declared righteous before God. "[We]...know that a man is not justified by observing the law, but by faith in Jesus Christ,"(Gal. 2:15,16). Justification is a legal, forensic declaration of freedom from the guilt of sin and from the condemnation of God (Romans 5:18-20). John Murray writes, "Justification...is an act of God accomplished in time wherein God passes judgment with respect to us as individuals," (Collected Writings, vol. 2 p. 203).
The Reformation doctrine of justification and the nature of saving faith, or "true faith" is that it is the obedience of Christ, and his death and resurrection, the sum his whole life and being en toto that justifies the sinner. The righteouness of Christ is imputed to the one who has faith (Romans 3:22; 4:16).
The nature of saving faith, according to Murray is not abstract; it is not in the form of an ethereal concept abiding alone by itself, "hanging in the air" as it were. On the contrary, Murray contends, "Faith is always joined with repentance, love and hope. A faith severed from these is not the faith of the contrite and therefore it is not the faith that justifies," (op cit. p217).
Murray emphasizes the importance of knowing that a faith that justifies is a faith that works; but he also affirms the lack of works in the process--or act--of justification. "While it makes void the gospel to introduce works in connection with justification, nevertheless works done in faith, from the motive of love to God, in obedience to the revealed will of God and to the end of his glory are intrinsically good and acceptable to God. As such they will be the criterion of reward in the life to come," p.221).
Murray draws a line of demarcation between the forensic act and the result of justification in viewing good works as impetus for reward. On the contrary, good works are not the instrument of justification. But at the same time, a faith that saves is a faith that is fused together with repentance.
This gives us reason for pause and ponder the relation between justification and sanctification. The two must be kept separate, otherwise sinners are caught in a quagmire of works-righteousness. It is in this regard that Protestants maintain that justification is a legal forensic act, a declaration of freedom from guilt before a holy God, and a having a temporal aspect as opposed to the progressive aspect of sanctification meted out in the life of the one who is justified.
The main question regards the faith that justifies (one not devoid of repentance, love and hope) and its relation to the idea that that which stems from this faith (works) is not a fusion of justifying and sanctifying faith. We are saved by grace through faith (Eph. 2:8).
One thing is certain therefore, and that is that the faith that justifies is the lone instrument by which a sinner is forgiven, but that faith is never devoid of repentence, a turning from sin with a whole-hearted love for God and his son. "Repent and believe the good news (Mark 1:15b). The crux of the matter as it concerns the voice of the Reformation is what the nature of saving faith is regarding its essence, and how that faith, as an instrument, serves and relates to the twin pillars of salvation in justification and sanctification. That is not all, for the concept of calling and union with Christ are involved...for a later discussion.