Irenaeus, writing in the late second century AD, was combatting a heresy that had come along and proved to be a grave threat to the church of Jesus Christ. While, at other points in the history of the early church, the threat came from those who denied that Christ was God, the threat Irenaeus was facing was just the opposite. He was, rather, embattling a movement that denied that Christ was human. This movement, referred to as Gnosticism, worked from their fundamental premise that matter was evil. The God described in the Old Testament was not the true God, but rather a lesser, evil deity, who created the world—he had to be an evil god because he created matter. The Gnostics, correspondingly, could not conceive of a salvation that was in any way founded on the incarnation. The truly good God, who is pure spirit, could not possibly have gone about the process of providing redemption by an act of incarnation, an act of enfleshment, because matter and flesh are evil. Therefore the Gnostics denied that there really was an act of incarnation. Rather, Christ only apparently took on human flesh. And Christ did not enter the world to provide salvation by his death on the cross. In fact, Christ left the human body he had temporarily assumed before the crucifixion; the man Jesus died on the cross, not the Christ who had simply been using his body. Christ came to provide freedom from the God of the Old Testament. Christ does this, not by incarnation, death, and resurrection, but by the impartation of some esoteric knowledge, a “gnosis,” that lifts the soul to higher plane above the material, fleshly world.
Hans Urs von Balthasar, in his book, The Scandal of the Incarnation: Irenaeus Against the Heresies, describes very well exactly what an “insidious” threat this Gnosticism was to the early church:
“So called gnosis” was an enormous temptation in the early Christian church. By contrast, persecution, even the bloodiest, posed far less of a threat to the Church’s continuing purity and further development. Gnosticism had its roots in late antiquity, drew on oriental and Jewish sources, and multiplied into innumerable esoteric doctrines and sects. Then, like a vampire, the parasite took hold of the youthful bloom and vigour of Christianity. What made it so insidious was the fact that the Gnostics very often did not want to leave the church. Instead, they claimed to be offering a superior and more authentic exposition of Holy Scripture, though, of course, this was only for the “superior souls” (“the spiritual,” “the pneumatic”); the common folk (“the psychic”) were left to get on with their crude practices. It is not hard to see how this kind of compartmentalizing of the Church’s members, indeed of mankind as whole, inevitably encouraged not only an excited craving for higher initiation, but almost an unbounded arrogance in those who had moved from mere “faith” to real, enlightened “knowledge.”
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From this very general description, we can see that Gnosticism is radically anti-Christian. Irenaeus, with great perspicacity, understood this, and show it up for what it was. For him, Christianity is about the divine and spiritual Word becoming flesh and body. The redemption depends on the real Incarnation, the real suffering on the cross, and the real resurrection of the flesh. All three of these are a scandal for Gnosticism.
Against the Gnostics, it was important for Irenaeus to show that Christ was not some spiritual being who merely for a short time lived inside a human person. It was important to demonstrate that the New Testament teaching was that there was a true union of divine and human in the man Christ Jesus, and that this divine-human person, by his life, death, and resurrection, provided redemption for all those who put their trust in him. And it was also important to show that Christ did not come to save us from the Old Testament God, or from inferior Old Testament conceptions of what God was like. It was important to demonstrate that the God of the Old Testament was, indeed, “the God and Father of our Lord Jesus Christ.” And it was important to show that it was this very same Old Testament God who initiated the incarnation of the Christ.
With this background, we see why so much of Irenaeus’s writing was focused on the incarnation. And we can also see, even today, how certain sectors of the Christian church are bringing various elements of this ancient gnostic heresy forward into our day, while still wanting to be thought of as Christian. In various ways, they deny the full implications of what it means for Christ to have become truly human, and they also deny the portrayal of God in the Old Testament, arguing that Christ came to save us from those Old Testament conceptions of God. In this light, then, I encourage you to read and meditate on this selection from Irenaeus’s Proof of the Apostolic Preaching, chaps. 37-39. The translation, again, is that of John Behr.
 In this way, He gloriously accomplished our salvation and fulfilled the promise made to the patriarchs and dissolved the old disobedience—the Son of God become the Son of God and the Son of Abraham: for, in accomplishing and recapitulating these things in himself, in order to obtain life for us, “the Word of God became flesh” by the economy of the virgin in order to undo death and vivify man, for we were in the prison of sin, we who have become sinners and fallen under the power of death.
 Rich in mercy was God the Father: He sent the creative Word, who, coming to save us, was in the same place and situation in which we were when we lost life, breaking the bonds of the prison; and His light appeared and dispelled the darkness of the prison, and sanctified our birth and abolished death, loosening the same bonds by which we were trapped.
And if one does not accept His birth from a Virgin, how can he accept His resurrection from the dead? . . .
 So, if He was not born, neither did He die; and if he did not die; neither was he raised from the dead, death is not conquered nor its kingdom destroyed; and if death is not conquered, how are we to ascend to life, having fallen under death from the beginning”
So those who reject the salvation of man and do not believe of God, that he will raise them from the dead, they also despise the birth of our Lord, which he underwent for us, the Word of God become flesh, that he demonstrate the resurrection of the flesh and be preeminent in all things: in heaven, for He is the firstborn of the Father’s counsel, the perfect Word, guiding and governing all things; while on earth, as He was the firstborn of the Virgin, a man righteous, holy, pious, good, pleasing to God, perfect in all things; saving all who follow His tracks from Hell, for he is the firstborn from the dead, and the Author of the life of God.
December 15, 2013