Adam, again: why Jesus’s humanity matters
31st March 2023
Kirsten Mackerras looks at how the early church theologian, Irenaeus, developed a biblical theology that confronted second century challenges to Christ’s humanity.
‘The Word became flesh, and made his dwelling among us’ (John 1:14). These familiar words were deeply contentious in the generations after they were written. Greek philosophy had long preferred the logical to the material, but in the second century some went further: they said the physical world was the source of evil. These people wanted a saviour to deliver them from fleshly existence, not one who became mired in it himself. As the second century church explained their faith to their culture, they had to discern which parts of the Christian story were essential and non-negotiable. Chief among those who took up this task was Irenaeus, bishop of Lyons (active c. AD 175–95), an important theologian who helped the church clarify what it believed about Christ.
Irenaeus’s main opponents are often called ‘gnostics’, from the Greek word for knowledge. Irenaeus himself called them ‘Valentinians’. The Valentinians believed in many divine beings who had different levels of power. In their view, the world was created by the demiurge, a low-level deity who inspired the Old Testament. They regarded matter as evil, the source of pain and error. The Saviour came to rescue some elite humans from this world and its incompetent, malevolent god. This meant the Valentinians rejected the Creator and the Old Testament; their Christ opposed everything that came before him. And because flesh was bad, they generally denied that Christ had been truly human. Some of them taught that a divine being had come upon the human Jesus at his baptism (an adoptionist Christology); others that Jesus only seemed to have human flesh and to suffer (docetism). While Irenaeus affirmed Christ’s divinity, he spent much more time demonstrating his humanity.
Jesus as a second Adam
In response to the Valentinians, Irenaeus developed a biblical theology that showed how Christ shared the purpose of the Old Testament God. A key idea in his theology is ‘recapitulation’: Christ retraced the steps of Adam and other Old Testament characters, substituting his obedience for their disobedience. As humanity’s representative, Christ’s experience of human life undoes the consequences of our rebellion. This way of reading the Bible was inspired by Paul, who described Jesus as the new Adam (Romans 5:12-21; 1 Corinthians 15:22, 44-49; cf. Ephesians 1:10). However, Irenaeus expanded Paul’s ideas to create a theological framework which could address the new challenges his generation faced. Parts of Irenaeus’s recapitulation theology may seem strange to us, but it was a fruitful approach in his time. And underneath this theology are familiar principles about the Bible: the Old and New Testaments tell the same story; the apostles’ account of the gospel is authoritative; and we should interpret everything within the story of Jesus. Many of the methods of Scripture interpretation we use today are first attested in Irenaeus.
By recapitulation, Irenaeus meant that Jesus’s advent is a new beginning for humanity, to fix our mistakes and change the end of the story. The Father has not abandoned creation, but sent his Son to get his plans for it back on track. In Against Heresies, one of only two surviving texts by Irenaeus, he put it like this:
When Christ became incarnate, and was made man, He commenced afresh the long line of human beings, and furnished us […] with salvation; so that what we had lost in Adam—namely, to be according to the image and likeness of God—that we might recover in Christ Jesus. 
Having helped to create Adam, the Son stepped inside his handiwork to save Adam and his descendants. Jesus had to become like the people who had rebelled against the Father to bring reconciliation; he had to become like the devil’s captives so their captivity could be overturned.
Christ and the Old Testament
The Valentinians pitted Christ against the Old Testament. They wanted a saviour to deliver them from the creator’s mistakes. In Irenaeus’s eyes, Christ’s fulfilment of prophecy proves that he shared the goals of the Old Testament God. For example, the incarnation fulfilled God’s promises to give Abraham children and to establish an eternal Davidic king. But, said Irenaeus, this promise and fulfilment only works if both testaments have the same author.
Jesus’s temptation in the wilderness shows how he recapitulated Old Testament experiences. Like Moses and Elijah, Jesus fasted for forty days, so that like Adam, he might be tempted with food. Irenaeus concluded that Jesus was dependent upon food and thus fully human. And Jesus would not have quoted the Mosaic law if it came from a low-grade deity; a higher God’s words would have given him more power. Irenaeus concluded that Christ’s faithfulness in temptation cancelled humanity’s disobedience and neutered Satan’s power over us.
The culmination of Christ’s obedience was his crucifixion. He experienced the moral struggle each of us faces, but remained obedient even in death. The parallels with Adam are many: through a man death conquered humanity, and through a man we receive victory over it. Humanity fell beside a tree, and was redeemed on one. As Adam and Eve were created on the sixth day, so Jesus died on the sixth day of the week. This last parallel shows that the crucifixion was a moment of second creation for humanity, where we were brought out of death and into life.
Jesus retraces our life experiences
Irenaeus also found something redemptive in Christ’s experience of ordinary human life. By experiencing each stage of life, he enables people in that life stage to be reconciled to God. Irenaeus believed that Jesus was nearly fifty when he died, proposing the idea that he approached close enough to old age to save the elderly. Irenaeus sees that as Jesus retraced the steps of Adam and Israel, so he walked through the major experiences of human life. By doing so, he made them a place where union with God and immortality could be gained.
In Irenaeus’ biblical theology, as Jesus recapitulated the life of Adam, so Mary recapitulated and redeemed the actions of Eve. Both women were visited by an angelic being, but while Eve’s disobedience brought about the fall, Mary’s obedience made her instrumental in redemption. Eve was the mother of all the living, and Mary mothered the source of eternal life. By assisting in salvation, Mary enabled the gendered shame from the fall to be removed.
Recapitulation and Christ’s humanity
Recapitulation is a powerful argument against docetism, the belief that Christ only seemed human, because it shows that Christ needed to share our humanity to save us. The Valentinians thought that he only appeared to have human flesh. Irenaeus responded, ‘What he was, that he also appeared to be.’ For a lot of theologians, the virgin birth demonstrates Christ’s deity. Irenaeus used it to prove his humanity: if Christ did not receive human flesh from Mary, why was she involved in his birth at all? If Christ was not human, he could not undo humanity’s errors. If Christ could not suffer, he did not die for us.
Irenaeus used the virgin birth to create another parallel with Adam. To recapitulate Adam, Christ needed to be Adam's descendent, but he also needed a birth like Adam’s. Only a virgin birth could fulfil both criteria. As Jesus’s birth was fatherless, so was Adam formed from ‘virgin’ soil, without male seed. Irenaeus says:
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.
As the new Adam, Jesus was the first in a new series of humans: those who are reconciled to God and given immortality. The virgin birth is essential to Christ’s ability to recreate humanity.
Images of salvation
Finally, Irenaeus used recapitulation to describe the salvation Jesus won by defeating evil. Recapitulation is the restoration of right headship—in both Greek and Latin, ‘recapitulation’ comes from the word for head. Hence recapitulation means that humans are restored from Satan’s tyranny to Christ, their true head. Using striking imagery, Irenaeus described how Christ descended into humanity’s imprisonment, for a human had to regain what was lost when Satan defeated humanity. Then, gathering us inside himself, he broke that prison open. The gates, as it were, had to be unlocked from inside for the victory to be legitimate. The deliverer also needed to be divine, since Satan’s conqueror had to be stronger than him. Through his obedience, Christ destroyed humanity’s enemy and set us free.
This is not the only salvation metaphor Irenaeus used. Christ replaced humanity’s disobedience with his own obedience; this is the language of substitution. Christ achieved reconciliation with God, propitiation, and the remission of sin. Elsewhere Irenaeus said that humans could only escape mortality if human flesh were united with something incorruptible. But since humans are not naturally immortal, a human had to defeat sin and death, and then share his victory with others. Jesus grants this upgraded, immortal humanity to us through union with himself. The resurrection was proof of Christ’s victory, at the cross and in every battle prior.
Christ’s essential humanity
Irenaeus’s opponents took Christ’s divinity for granted, but they questioned his humanity. This is why Irenaeus emphasised the incarnation. The result is the richest meditation on the incarnation that the church at that time had produced. Our culture is the opposite: Jesus’s human existence is historically verified, and more doubt is directed towards his deity. Authors like Irenaeus remind us of the importance of Christ’s humanity, which we might otherwise take for granted. It is precisely because Irenaeus’s context raised different challenges to the gospel that he can teach us so much. He shows us our faith from a different angle, enriching our understanding of it. Similarly, Irenaeus reminds us of the importance of holding the Old and New Testaments together. Without the Old Testament, our picture of Christ will be incomplete. We misinterpret him if, like the Valentinians, we place him against another background.
Irenaeus emphasised that it is Christ’s likeness to us, together with his divinity, that enables him to save. He has ennobled human experience. The incarnation dignifies the ordinary as the place where God wants to work. And, as the writer to the Hebrews says, this means he can sympathise with our weaknesses. He is not merely the God of the spiritual, or interested in saving ‘souls’. He wants to save our bodies and the material world as well. While the Valentinians thought that only a few special believers could understand the truth, Irenaeus offered the possibility of salvation to all people. Irenaeus’s idea of recapitulation shows a God who is committed to the world he made, patiently retracing the steps of his disobedient creatures to grant us the benefits of his own faithfulness.