Simply Described, yet Devastatingly Accomplished

What it means to be justified (which means imputation of righteousness!) as a Christian is perfectly described by early church father, John Chrysostom (349-407 AD):

And what has he done? "Him that knew no sin He made to be sin, for you." For if he had achieved nothing elsebut done only this, think how great a thing it is to give His Son for those that had outraged Him. But now he has truly achieved mighty things, and besides, has allowed him that did no wrong to be punished for those who had done wrong. Yet Paul did not say this, but mentioned that which is far greater than this. What then is this? "Him that knew no sin," he says, Him that was righteousness itself, "He made sin," that is allowed Him to be condemned as a sinner, as one cursed to die. "For cursed is he that hangs on a tree" (Gal. 3.13). For to die like this was far greater than simply to die; and this he also elsewhere implies, saying, "Becoming obedient unto death, even the death of the cross" (Phil. 2.8). For this thing carried with it not only punishment, but also disgrace.

Reflect therefore what great things He bestowed on you. For it would indeed be a great thing for even a sinner to die for anyone whatever; but when He who undergoes this is righteous and yet dies for sinners; and not only dies, but even dies as one cursed; and not as cursed only, but thereby freely bestows upon us those great benefits which we never anticipated (for he says "we might become the righteousness of God in Him)-what words, what thought shall be adequate to realize these things? "For the Righteous One he made a sinner," he says, "that He might make the sinners righteous." Indeed rather, he did not even say this, but what was greater by far; for the word he employed is not he habit [sinner], but the quality [of sin] itself.

For this is the righteousness of God, when we are justified not by works, in which case it would be necessary that not even a spot should be found, but by grace, in which case all sin is done away. And this, at the same time that it does not allow us to be lifted up (for it is entirely the free gift of God), teaches us also the greatness of what is given. For what came before was a righteousness of the law and of works, but this it the righteousness of God."

Nick Needham notes, "Here is what the Reformers were to call "the wonderful exchange": Christ being made sin with humanity's sin, so that we might become righteous with a divine righteousness."

Quotations taken from:

Needham, Nick. "Justification in the Early Church Fathers." quoting John Chrysostom's work, "Homilies on 2Corinthians 11.5." All quotations coming from "Justification in Perspecitive" edited by Bruce L. McCormack, (Baker: Grand Rapids, 2006), 35.