Christ’s active obedience is His perfect obedience to the Law of God. Christ’s passive obedience is His taking our sins upon Himself, being nailed to the cross, and suffering the punishment of God’s wrath unto death—the wrath we deserved. Historically, the majority of Protestants have agreed that both Christ’s active and passive obedience is imputed to believers upon the exercise of saving faith. But, some have disagreed.
Some, particularly within the Federal Visionist and Arminian camps (cf. Berkhoff, Systematic Theology, 515), deny the imputation of the active obedience of Christ to the believer. They might claim that forgiveness of sins is all the Christian needs. Then, by virtue of his own righteousness or obedience, he will reach final justification (or something along those lines). The believer only need be rendered innocent of their sin.
This obviously denies the need for an imputed positive righteousness.
The problem, however, is that this denies very clear Scriptural data. For example, Romans 4:11 says:
And he received the sign of circumcision, a seal of the righteousness of the faith which he had while still uncircumcised, that he might be the father of all those who believe, though they are uncircumcised, that righteousness might be imputed to them also…
Those who deny the imputation of Christ’s righteousness need to at least admit, in light of Romans 4, that there is a righteousness imputed (counted to) those with faith. The question, then, is whose righteousness is it? It can’t be the original righteousness of the believer. This righteousness is coming from somewhere else and is counted to the believer. That’s what imputation is. It’s an alien righteousness coming to be possessed by someone without their own righteousness.
The objector may claim that v. 12 makes clear that which was lacking in v. 11. Verse 12 reads as follows:
… and the father of circumcision to those who not only are of the circumcision, but who also walk in the steps of the faith which our father Abraham had while still uncircumcised.
“Ah,” our pretend objector might say, “you see, this righteousness is imputed because of faith plus walking according to that faith.” This is not what the text says. The person who walks faithfully walks because of faith, a faith which Paul has already claimed is the instrument of this imputed righteousness (vv. 9, 10).
Moreover, there is a distinction between faith on the one hand and the outworking of that faith on the other; otherwise, steps would not be the indirect object with faith being the direct object. If our interlocutor wanted to conflate the steps of faith with faith itself, they would simply need to explain why Paul doesn’t use the adjectival form pistos instead of the noun pistis. Pistos would describe someone who obeys from a heart of faith—a faithful person. It’s used of Epaphras in Colossians 1:7. In that case, verse 12 might read as follows: “… and the father of circumcision to those who not only are of the circumcision, but who are faithful…” But, as you can tell, not even the immediate context would allow for such a reading since Paul wants to describe the faith that was possessed by Abraham, antecedent to his obedience in circumcision. There is a necessary distinction between faith as something which is possessed, and obedience which is something that is performed as a result of the faith possessed.
Therefore, with Paul, we should conclude that Christ “became for us wisdom from God—and righteousness and sanctification and redemption… (1 Cor. 1:30).”