What does ‘for righteousness’ mean? The word ‘for’ is to be understood in the sense of ‘as’ or ‘as if it were (which it is not)’, not in the sense of ‘in the place of’ or ‘instead of’. The difference is this: ‘instead of righteousness’ could mean that faith possessed some merit so that God was content that, having failed to give him righteousness earned under the law, we instead gave him righteousness in the form of faith which he treats as an acceptable – albeit inferior – substitute. On the other hand ‘as righteousness’ or ‘as if it were righteousness’ need only mean that God treats faith as the necessary condition of salvation.
Paul quotes from Genesis 15:6, but what exactly do these words mean? Does Moses teach that faith is a substitute for works and that God is willing to accept it in those who lack the works which the law requires, and to regard their faith as having the same merit which the law would otherwise give them? Is faith accepted as a substitute for obedience because it contains equivalent merit? Certainly not, for verse 8 tells us that it is God who is doing the justifying and not man. In case we had any doubt, Paul elsewhere explains that what faith lays hold of is a righteousness earned by Christ under the law and imputed to us. So then, after all, it was a righteousness that came from the law for this is the only place that righteousness can ever come from, however it was Christ that earned it and not us. Faith has no merit. The law says nothing about believing, but only about doing. Faith simply looks, but does not do. It leaves undone all the commandments that God’s law demands, and yet God has made it the condition of justification.