The following is taken from Ligon Duncan’s “Did the Fathers Know the Gospel?”:
Dr. Duncan’s second piece of evidence is from the
Epistle to Diognetus. The date for this epistle is not exactly certain, but it
was most likely written in the second century, possibly the third. At 57’07”
into the video Dr. Duncan quotes from the ninth paragraph of the Epistle to
Diognetus:
But when our wickedness had reached
its height, and it had been clearly shown that its reward, punishment and
death, was impending over us; and when the time had come which God had before
appointed for manifesting His own kindness and power, how the one love of God,
through exceeding regard for men, did not regard us with hatred, nor thrust us
away, nor remember our iniquity against us, but showed great long-suffering,
and bore with us, He Himself took on Him the burden of our iniquities, He gave
His own Son as a ransom for us, the holy One for transgressors, the blameless
One for the wicked, the righteous One for the unrighteous, the incorruptible
One for the corruptible, the immortal One for those who are mortal. For what
other thing was capable of covering our sins than His righteousness? By what
other one was it possible that we, the wicked and ungodly, could be justified,
than by the only Son of God? O sweet exchange! O unsearchable operation! O
benefits surpassing all expectation! That the wickedness of many should be hid
in a single righteous One, and that the righteousness of One should justify
many transgressors! (Epistle to Diognetus, 9)
Can a Catholic affirm this quotation
from the Epistle to Diognetus? Again, most definitely. That Christ became a
ransom for us is taught not only by Scripture, but also by the Catholic
Catechism, which reads:
The Scriptures had foretold this
divine plan of salvation through the putting to death of “the righteous one, my
Servant” as a mystery of universal redemption, that is, as the ransom that
would free men from the slavery of sin. (CCC 601) … Consequently, St. Peter can
formulate the apostolic faith in the divine plan of salvation in this way: “You
were ransomed from the futile ways inherited from your fathers. . . with the
precious blood of Christ, like that of a lamb without blemish or spot. He was
destined before the foundation of the world but was made manifest at the end of
the times for your sake.” Man’s sins, following on original sin, are punishable
by death. By sending his own Son in the form of a slave, in the form of a
fallen humanity, on account of sin, God “made him to be sin who knew no sin, so
that in him we might become the righteousness of God.” (CCC 602) The redemption
won by Christ consists in this, that he came “to give his life as a ransom for
many” (Mt 20:28), that is, he “loved [his own] to the end” (Jn 13:1), so that
they might be “ransomed from the futile ways inherited from [their] fathers” (I
Pt 1:18). (CCC 622)
When the author of the Epistle to Diognetus says
that only Christ’s righteousness was capable of covering our sins, he means
that only Christ’s righteousness could make atonement for our sins. The author
is not talking about Christians being simul
iustus et peccator or possessing Christ’s righteousness by way
of an extra nos imputation.
The author is writing about Christ’s sacrificial atonement. Christ is the
perfect Lamb, and because He is perfect, only He could offer to the Father on
our behalf the perfect sacrifice that atoned for our sins, procuring for us the
grace by which our sins are removed. The author of the Epistle to Diognetus
explains this when he speaks of our wickedness being “hid in a single righteous
One.” That is the sense in which Christ’s righteousness was “capable of
covering our sins,” through His work of sacrificial atonement offered to God,
not through an imputation of righteousness that hides our underlying
wickedness. Such a notion would have been entirely repugnant to the Fathers.
The doctrine being taught by the author of the Epistle to Diognetus is that
Christ took our sins on Himself as our priest and mediator. Our sins were
hidden in Him not by imputation, but by mediation. Christ made atonement for
them by becoming our sacrificial lamb, and offering Himself in self-sacrificial
love to the Father on our behalf. He is both perfect priest and perfect
sacrifice. He as priest and perfect sacrifice takes upon Himself the burden of
our iniquities, including suffering and death; we in turn receive from Him the
grace and agape by
which we are justified. That is the nature of the “sweet exchange” to which he
refers. Christ freely gave Himself up to the Father, suffering in His body and
soul for our sins (see here), and we in return
receive the infused grace and agape by
which we are justified. So this selection from the Epistle to Diognetus is not
evidence of even an implicit Reformed conception of the gospel, because it is
fully compatible with the Catholic doctrine of redemption, and best understood
as teaching the Catholic understanding of Christ’s redemptive work.