Christ as the New Adam
To counter his Gnostic opponents, Irenaeus significantly develops Paul's presentation of Christ as the Last Adam.
Irenaeus' presentation of Christ as the New Adam is based on Paul's Christ-Adam parallel in Romans 5:12-21. Irenaeus uses this parallel to demonstrate that Christ truly took human flesh.
Irenaeus considers it important to emphasize this point, because he understands the failure to recognize Christ's full humanity [was] the bond linking the various strains of Gnosticism together, as seen in his statement that "
according to the opinion of no one of the heretics was the Word of God made flesh." [67;
Ad Haer, III.11.3]
Irenaeus believes that unless the Word became flesh, humans were not fully redeemed.[68] He explains that by becoming man, Christ restored humanity to being in the image and likeness of God, which they had lost in the Fall of man [69][70] Just as Adam was the original head of humanity through whom all sinned, Christ is the new head of humanity who fulfills Adam's role in the Economy of Salvation.[71] Irenaeus calls this process of restoring humanity recapitulation.[72]
For Irenaeus, Paul's presentation of the Old Law (the Mosaic covenant) in this passage indicates that the Old Law revealed humanity's sinfulness but could not save them. He explains that "
For as the law was spiritual, it merely made sin to stand out in relief, but did not destroy it. For sin had no dominion over the spirit, but over man."[73]
Since humans have a physical nature, they cannot be saved by a spiritual law. Instead, they need a human Savior. This is why it was necessary for Christ to take human flesh.[73] Irenaeus summarizes how Christ's taking human flesh saves humanity with a statement that closely resembles Romans 5:19,
"For as by the disobedience of the one man who was originally moulded from virgin soil, the many were made sinners, and forfeited life; so was it necessary that, by the obedience of one man, who was originally born from a virgin, many should be justified and receive salvation."[74]
The physical creation of Adam and Christ is emphasized by Irenaeus to demonstrate how the Incarnation saves humanity's physical nature.[75]
Irenaeus emphasizes the importance of Christ's reversal of Adams's action. Through His obedience, Christ undoes Adam's disobedience.[76] Irenaeus presents the Passion as the climax of Christ's obedience, emphasizing how this obedience on the tree of the Cross
Phil. 2:8 undoes the disobedience that occurred through a tree Gen. 3:17.[77]
Irenaeus' interpretation of Paul's discussion of Christ as the New Adam is significant because it helped develop the Recapitulation theory of atonement. Irenaeus emphasizes that it is through Christ's reversal of Adam's action that humanity is saved, rather than considering the Redemption to occur in a cultic or juridical way.[78][79]