A central purpose of Against Heresies was to refute the heretical teachings of Gnosticism, which flourished during the early church period. Because many Gnostics held that spiritual knowledge was to be arrived at through interior means, and because many also claimed to have access to ‘secret knowledge’ about the nature of the universe, Gnostic beliefs varied widely. Indeed, Gnostic beliefs were so diverse that modern scholars generally agree that, even during the height of Gnosticism in the 2nd century, the various Gnostic sects never shared a well-defined body of doctrine with one another.
One of the ways Irenaeus countered the complex array of Gnostic beliefs was to assert that true knowledge of spiritual reality is to be found by relying on the pillars of Christian orthodoxy: the Scriptures, the traditions handed down from the apostles, and the teachings of the apostles’ successors. By directing Christians to the pillars of orthodoxy, Irenaeus—who remains a celebrated figure in the Catholic, Protestant, and Eastern Orthodox Churches—greatly narrowed the range of arguments available to Christian theists seeking to answer the problem of evil.
In the excerpt below, Irenaeus discusses the source of evil and imperfection, which he asserts originates from man’s disobedience and lack of faith.
CHAPTER XXXIX
MAN IS ENDOWED WITH THE FACULTY OF DISTINGUISHING GOOD AND EVIL; SO THAT, WITHOUT COMPULSION, HE HAS THE POWER, BY HIS OWN WILL AND CHOICE, TO PERFORM GOD’S COMMANDMENTS, BY DOING WHICH HE AVOIDS THE EVILS PREPARED FOR THE REBELLIOUS.
1. Man has received the knowledge of good and evil. It is good to obey God, and to believe in Him, and to keep His commandment, and this is the life of man; as not to obey God is evil, and this is his death. Since God, therefore, gave [to man] such mental power (magnanimitatem) man knew both the good of obedience and the evil of disobedience, that the eye of the mind, receiving experience of both, may with judgment make choice of the better things; and that he may never become indolent or neglectful of God’s command; and learning by experience that it is an evil thing which deprives him of life, that is, disobedience to God, may never attempt it at all, but that, knowing that what preserves his life, namely, obedience to God, is good, he may diligently keep it with all earnestness. Wherefore he has also had a twofold experience, possessing knowledge of both kinds, that with discipline he may make choice of the better things. But how, if he had no knowledge of the contrary, could he have had instruction in that which is good? For there is thus a surer and an undoubted comprehension of matters submitted to us than the mere surmise arising from an opinion regarding them. For just as the tongue receives experience of sweet and bitter by means of tasting, and the eye discriminates between black and white by means of vision, and the ear recognises the distinctions of sounds by hearing; so also does the mind, receiving through the experience of both the knowledge of what is good, become more tenacious of its preservation, by acting in obedience to God: in the first place, casting away, by means of repentance, disobedience, as being something disagreeable and nauseous; and afterwards coming to understand what it really is, that it is contrary to goodness and sweetness, so that the mind may never even attempt to taste disobedience to God. But if any one do shun the knowledge of both these kinds of things, and the twofold perception of knowledge, he unawares divests himself of the character of a human being.
2. How, then, shall he be a God, who has not as yet been made a man? Or how can he be perfect who was but lately created? How, again, can he be immortal, who in his mortal nature did not obey his Maker? For it must be that thou, at the outset, shouldest hold the rank of a man, and then afterwards partake of the glory of God. For thou dost not make God, but God thee. If, then, thou art God’s workmanship, await the hand of thy Maker which creates everything in due time; in due time as far as thou art concerned, whose creation is being carried out. Offer to Him thy heart in a soft and tractable state, and preserve the form in which the Creator has fashioned thee, having moisture in thyself, lest, by becoming hardened, thou lose the impressions of His fingers. But by preserving the framework thou shalt ascend to that which is perfect, for the moist clay which is in thee is hidden [there] by the workmanship of God. His hand fashioned thy substance; He will cover thee over [too] within and without with pure gold and silver, and He will adorn thee to such a degree, that even “the King Himself shall have pleasure in thy beauty.” But if thou, being obstinately hardened, dost reject the operation of His skill, and show thyself ungrateful towards Him, because thou weft created a [mere] man, by becoming thus ungrateful to God, thou hast at once lost both His workmanship and life. For creation is an attribute of the goodness of God but to be created is that of human nature. If then, thou shalt deliver up to Him what is thine that is, faith towards Him and subjection, thou shalt receive His handiwork, and shall be a perfect work of God.
3. If, however, thou wilt not believe in Him, and wilt flee from His hands, the cause of imperfection shall be in thee who didst not obey, but not in Him who called [thee]. For He commissioned [messengers] to call people to the marriage, but they who did not obey Him deprived themselves of the royal supper. The skill of God, therefore, is not defective, for He has power of the stones to raise up children to Abraham; but the man who does not obtain it is the cause to himself of his own imperfection. Nor, [in like manner], does the light fail because of those who have blinded themselves; but while it remains the same as ever, those who are [thus] blinded are involved in darkness through. their own fault. The light does never enslave any one by necessity; nor, again, does God exercise compulsion upon any one unwilling to accept the exercise of His skill. Those persons, therefore, who have apostatized from the light given by the Father, and transgressed the law of liberty, have done so through their own fault, since they have been created free agents, and possessed of power over themselves.
4. But God, foreknowing all things, prepared fit habitations for both, kindly conferring that light which they desire on those who seek after the light of incorruption, and resort to it; but for the despisers and mockers who avoid and turn themselves away from this light, and who do, as it were, blind themselves, He has prepared darkness suitable to persons who oppose the light, and He has inflicted an appropriate punishment upon those who try to avoid being subject to Him. Submission to God is eternal rest, so that they who shun the light have a place worthy of their flight; and those who fly from eternal rest, have a habitation in accordance with their fleeing. Now, since all good things are with God, they who by their own determination fly from God, do defraud themselves of all good things; and having been [thus] defrauded of all good things with respect to God, they shall consequently fall under the just judgment of God. For those persons who shun rest shall justly incur punishment, and those who avoid the light shall justly dwell in darkness. For as in the case of this temporal light, those who shun it do deliver themselves over to darkness, so that they do themselves become the cause to themselves that they are destitute of light, and do inhabit darkness; and, as I have already observed, the light is not the cause of such an [unhappy.] condition of existence to them; so those who fly from the eternal light of God, which contains in itself all good things, are themselves the cause to themselves of their inhabiting eternal darkness, destitute of all good things, having become to themselves the cause of [their consignment to] an abode of that.
Irenaeus of Lyons, Against Heresies, edited by Paul A. Böer, Sr.