18 Therefore as by the offence of one judgment came upon all men to condemnation; even so by the righteousness of one the free gift came upon all men unto justification of life.
Paul does not mean by this that because one man sinned everybody else had to pay the price for it even though they had not committed the sin, for that would be unjust. Rather he says that from its beginning in Adam humanity derived both its existence and its sinfulness.
Some people think that because the condemnation was universal, the acquittal will also be universal. But this is not so, because not everyone believes.
What was Adam’s sin? Disobedience. What was Christ’s righteousness? Obedience, by which he obeyed the Father in his incarnation and in his suffering for mankind, as the apostle says: “Being found in human form, he humbled himself and became obedient unto death, even death on a cross.” Thus obedience overcame disobedience and the worse was condemned by the better.
What he says seems indeed to involve no small question: but if any one attends to it diligently, this too will admit of an easy solution. What then is the question? It is the saying that through the offense of one many were made sinners. For the fact that when he had sinned and become mortal, those who were of him should be so also, is nothing unlikely. But how would it follow that from his disobedience another would become a sinner? For at this rate a man of this sort will not even deserve punishment, if, that is, it was not from his own self that he became a sinner. What then does the word "sinners" mean here? To me it seems to mean liable to punishment and condemned to death. Now that by Adam's death we all became mortals, he had shown clearly and at large. But the question now is, for what purpose was this done? But this he does not go on to add: for it contributed nothing to his present object. For it is against a Jew that the contest is, who doubted and made scorn of the righteousness by One. And for this reason after showing that the punishment too was brought in by one upon all, the reason why this was so he has not added. For he is not for superfluities, but keeps merely to what is necessary. For this is what the principles of disputation did not oblige him to say any more than the Jew; and therefore he leaves it unsolved. But if any of you were to enquire with a view to learn, we should give this answer: That we are so far from taking any harm from this death and condemnation , if we be sober-minded, that we are the gainers even by having become mortal, first, because it is not an immortal body in which we sin; secondly, because we get numberless grounds for being religious (φιλοσοφίας]). For to be moderate, and to be temperate, and to be subdued, and to keep ourselves clear of all wickedness, is what death by its presence and by its being expected persuades us to. But following with these, or rather even before these, it has introduced other greater blessings besides. For it is from hence that the crowns of the martyrs come, and the rewards of the Apostles. Thus was Abel justified, thus was Abraham, in having slain his son, thus was John, who for Christ's sake was taken off, thus were the Three Children, thus was Daniel. For if we be so minded, not death only, but even the devil himself will be unable to hurt us. And besides there is this also to be said, that immortality awaits us, and after having been chastened a little while, we shall enjoy the blessings to come without fear, being as if in a sort of school in the present life, under instruction by means of disease, tribulation, temptations, and poverty, and the other apparent evils, with a view to our becoming fit for the reception of the blessings of the world to come.
I know certain men for whom the king of Nineveh, (who is the last to hear the proclamation and who descends from his throne, and forgoes the ornaments of his former vices and dressed in sackcloth sits on the ground, he is not content with his own conversion, preaches penitence to others with his leaders, saying, "let the men and beasts, big and small of size, be tortured by hunger, let them put on sackcloth, condemn their former sins and betake themselves without reservation to penitence!) is the symbol of the devil, who at the end of the world, (because no spiritual creature that is made reasoning by God will perish), will descend from his pride and do penitence and will be restored to his former position. To support this opinion they use this example of Daniel in which Nebuchadnezzar after seven years of penitence is returned to his former reign. [Dan. 4:24, 29, 33] But because this idea is not in the Holy Scripture and since it completely destroys the fear of God, (for men will slide easily into vices if they believe that even the devil, the creator of wickedness and the source of all sins, can be saved if he does penitence), we must eradicate this from our spirits. Let us remember though that the sinners in the Gospel are sent to the eternal fire [Mt. 25:41], which is prepared for the devil and his angels, about whom is said, "their worm will not die and their fire will not be extinguished" [Is. 66:24]... Moreover if all spiritual creatures are equal and if they raise themselves up by their virtues to heaven, or by their vices take themselves to the depths, then after a long circuit and infinite centuries, if all are returned to their original state with the same worthiness to all conflicting, what difference will there be between the virgin and the prostitute? What distinction will there be between the mother of the Lord and (it is wicked to say) the victims of public pleasures? Will Gabriel be like the devil? Will the apostles be as demons? Will the prophets be as pseudoprophets? Martyrs as their persecutors? Imagine all that you will, increase by two-fold the years and the time, take infinite time for torture: if the end for all is the same, all the past is then nothing, for what is of importance to us is not what we are at any given moment, but what we will be forever more.
No one is born without the intervention of carnal concupiscence, which is inherited from the first man, who is Adam, and no one is reborn without the intervention of spiritual grace, which is given by the second man, who is Christ.
God wants all those to whom grace comes through the righteousness of the One unto justification of life to be saved and come to the knowledge of the truth.
What has Adam’s guilt got to do with us? Why are we held responsible for his sin when we were not even born when he committed it? Did not God say: “The parents will not die for the children, nor the children for the parents, but the soul which has sinned, it shall die.” How then shall we defend this doctrine? The soul, I say, which has sinned, it shall die. We have become sinners because of Adam’s disobedience in the following manner.… After he fell into sin and surrendered to corruption, impure lusts invaded the nature of his flesh, and at the same time the evil law of our members was born. For our nature contracted the disease of sin because of the disobedience of one man, that is, Adam, and thus many became sinners. This was not because they sinned along with Adam, because they did not then exist, but because they had the same nature as Adam, which fell under the law of sin. Thus, just as human nature acquired the weakness of corruption in Adam because of disobedience, and evil desires invaded it, so the same nature was later set free by Christ, who was obedient to God the Father and did not commit sin.
[AD 366] Acacius of Caesarea on Romans 5:18