#concupiscence

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 [of original sin? Let us begin by affirming that] the soul [which] has sinned [shall] die. We [all] 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 [his nature was infected,] the ‘evil law’ of [all future mankind’s] 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 [by nature]. 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, [by failing to honor the law of God,] fell under the law of sin. Thus, just as human nature acquired the weakness of corruption 'in’ Adam because of [his] disobedience, [whereupon] 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– [restoring & preserving forever, through His sharing in human nature, the righteous purity that Adam lost].

Saint Cyril of Alexandria

When a man is born, he is already born with death, because he contracts sin from Adam. [Thus] everyone, even little children, have ‘broken God’s covenant’, not indeed in virtue of any personal action, but in virtue of mankind’s common origin in that single ancestor, in [whose corrupted nature] all have sinned. As infants cannot help being descended from Adam, so they cannot help being touched by the same sin, unless they are set free from its guilt by the baptism of Christ, [the new Adam]. All men for whom Christ died, died in the sin of the first Adam, and all who are baptized into Christ die to sin, [and to that carnal life ruled by it]. 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.

Saint Augustine of Hippo; Commentary on Romans 5