By Lizzie Self
In Book Three of Against Heresies, Saint Irenaeus responds to a request that he refute the doctrines of various heretics, and he proposes that this is a singular task. At the heart of the grievances between the Church and the heretics of his day was the debate over human knowledge: is man ignorant apart from God, or can he achieve pure knowledge by searching himself and receiving secrets from spiritual elite, such as the Gnostics and other heretics? Responding to this question, Irenaeus argues that the knowledge possessed by the Apostles––and all the faithful, through the deposit of faith–– is indeed perfect and cannot be found elsewhere. If acceptance of the incarnation is essential for salvation, then anything outside of it is ignorance and sin. Thus, it is in ignorance that heresy is devised, and heresy can be nothing but pure invention and empty convictions.
Irenaeus begins with defending the deposit of faith, and he opposes heretics by showing their truth to be changeable and doctrine unfounded. Heretics claim that their truth is that which is unaltered (Against Heresies, 3.1.1); yet, Irenaeus observes that the professions of heretics are inconsistent, and their attempt to defend this changeability by considering understanding to be a mystery residing in one man and then another amounts to increased ignorance at best. At its worst, this rejection of Scripture and Tradition is a choice to be exempt from salvation (Against Heresies, 3.1.2). Heretics suggest that knowledge comes from man himself, that he can ascend the material world by an internal understanding apart from God. This violates trust in God’s benevolence and inspires doubt that He wishes to bring all of His Creation into His knowledge. God withholds the power of coercing man into perfect knowledge because He respects what He has established; this is, as Irenaeus refers to it, the “ancient law of human liberty” (Against Heresy,3.37.1). Man would not be more like God if he understood Him perfectly. He is in His image because he was made free: “Man is possessed of free will from the beginning, and God is possessed of free will, in whose likeness man was created” (Against Heresy, 3.37.4).
The incarnation is nonsensical if God does not view man as good; there would be no reason for Him to free man from ignorance if He was not pursuing His own in love (Against Heresies, 3.23.2). Irenaeus emphasizes that man possesses the wherewithal to choose goodness if he depends upon the deposit of faith, its crux being the incarnation and Christ’s death. He explains why God has put His law of human liberty in place, when it seems that it would be so much easier if man did not have to willfully participate in His incorrupt, immortal life:
“This therefore was the [object of the] long-suffering God, that man, passing through all things, and acquiring the knowledge of moral discipline, then attaining to the resurrection from the dead, and learning by experience what is the source of his deliverance, may always live in a state of gratitude to the Lord, having attained from Him the gift of incorruptibility, that he might love Him more; … and that he may know himself, how mortal and weak he is.”(Against Heresies, 3.20.2)
The source of his deliverance is, of course, the incarnation and death of Christ. God makes His power complete by overcoming death, and death would not be overcome if this were not accomplished by its victim, man (Against Heresies, 3.18.7). Thus, it was necessary that God assumed human flesh. Anyone who does not profess that this is what Christ accomplished rejects the means of their own salvation (Against Heresies, 3.19.1).
This is the lie that Satan tells: man does not need to be saved, and so he does not need God to achieve an understanding of higher things and the power his heart desires. Satan blinds man by making him ignorant of the relationship God calls him to and ungrateful for the incarnation (Against Heresies, 3.20.1). Thus was Adam, in his ignorance and shame, driven from the Garden of Eden, not because he had somehow become evil in nature, but so that his sin should not continue, and he might be made free from it again (Against Heresies, 3.23.6). God’s favor, palpable in the pages of Scripture, shows man that he is good:
“Thus, the Fall comes to mean something very different from definite condemnation; rather, it is a sign by which man can be reminded of his own nature and see the choice before him; “He [God] pronounced no curse against Adam personally, but against the ground, in reference to his works, as a certain person among the ancients has observed: ‘God did indeed transfer the curse to the earth, that it might not remain in man’”(Against Heresies, 3.22.4).
Irenaeus never forgets to emphasize that man is made in God’s image, and even remarks that the eternal fire of Hell was prepared for Satan, the one who caused man to fall, not for man himself (Against Heresy, 3.23.3). Hope, then, depends upon trust in the incarnation as a sign of God’s love for humankind.
Man might protest that he does not experience God’s compassion because, in a state of ignorance, he cannot feel sorrow for his sin. Yet, Irenaeus supposes that because of the presence of Scripture and Tradition, man does not actually need to commit sin to be aware of it; ignorance, or unbelief, is a separation from the Word of God made flesh. Adam and Eve, having made man slave to death and blinded by ignorance, are delivered to immortal life by the truly human Virgin Mother and her Son (Against Heresies, 3.22.4). In rejecting Mary and Christ, man chooses utter ignorance; and in this ignorance, anything he conceives of is heresy. Augustine wrote truthfully, then, centuries later when he said that “this then is the origin of evil: man regards himself as his own light, and turns away from the light which would make himself a light if he set his heart on it.” Man must set his heart on it; he must give an active ‘yes’ to the Body of Christ to share in His life. Just as Adam was redeemed by the cleansing he underwent in the desert and through death, so must all of humankind willfully repent when they sense their sin, and still experience physical death, so that they can spend eternity with the Father (Against Heresy, 3.23.5).
All heresy is refuted, then, by a single blow: those who reject the incarnation and the death of Christ reject their own salvation. This is the fundamental Truth, and any attempts to understand the nature of humankind, any pursuit of knowledge, will be void without the insight of Christ’s actions. Heresy is sin, because heretics’ ignorance is willed. The deposit of faith is no hidden mystery, but good news to all equally. Heresy cannot be a positive evil, an evil with substance standing in opposition to God, but it must be a lack, an absence of goodness, stubbornly guarded by the proud hearts of men.
 Augustine. City of God. XIV, XIII.