The theological importance of Saint Irenaeus is due to two reasons:
The first reason: He lifted the mask that the Gnostic heresy covered its teachings with, claiming that its teachings were the true Christian faith, and by lifting this mask the church in his time was able to exclude this heresy from the church.
The second reason: He was so successful in identifying and defining the elements of the faith of the universal church, which the Gnostics denied or misinterpreted, that he deserves to be called the “founder of Christian theology.”
Irenaeus was not inclined to abstract theoretical thinking and did not strive to create theological discoveries that were not handed down from the apostles. On the contrary, he was always easily skeptical of any kind of abstract theoretical knowledge or science. Therefore, we find him saying in the book “Against Heresies”: [It is better for a person not to acquire knowledge or information about the reason for which any creature was created, but rather to believe in God and continue to love Him than to be puffed up with knowledge of this kind and this leads you to fall from the love of God, which is the life of man. And a person should not seek any other knowledge except the knowledge of Jesus Christ, the Son of God, who was crucified for us. Whoever seeks other knowledge using malicious questions and cunning and complex expressions will fall into impiety and impiety] (AH2:26:1).
Despite his cautious and skeptical attitude towards abstract theoretical theological teachings, as the famous patrist Johannes Quasten says, (1)Irenaeus is worthy of great status and unparalleled merit for the Christian faith, because he was the first to formulate the doctrinal terms for all the teachings of the Christian faith.
1- Saint Irenaeus’ teaching on the Trinity:
St. Irenaeus’s teaching on the Trinity is characterized by the affirmation that the one true God is the same Creator of the world, the same God of the Old Testament, and the same Father of the Word. Although Irenaeus does not investigate the relations of the three Persons to each other, he is convinced that the existence of the Father, the Son, and the Holy Spirit is clearly established in the history of the human race. The Father, the Son, and the Holy Spirit existed before the creation of the world, for, as he says, the words, “Let us make man in our image and likeness” (Gen. 1:26) are addressed by the Father to the Son and the Holy Spirit, those two Persons whom St. Irenaeus calls “the hands of God” (see AH 5:19:3; 5:28:1; 5:5:1). St. Irenaeus repeatedly explains that the Holy Spirit, together with the Word, fills the prophets with the anointing of revelation and that it is the Father who has arranged all these things. Therefore, the entire Old Testament economy of salvation is for Irenaeus an excellent lesson on the three Persons in the one God.
2- Saint Irenaeus’ teaching about Christ:
- Concerning the relationship between the Son and the Father:
St. Irenaeus says that no one can comprehend how the Son is born from the Father, and no one can understand the nature of this divine birth, and what name He gives it, because it is something that is beyond description or explanation. No one knows this relationship except the Father who begets the Son, and the Son who was born from the Father. Therefore St. Irenaeus says: “Since this birth cannot be expressed in words and is beyond comprehension, therefore those who try to establish and arrange births(2) “And they cannot be rational because they are trying to describe things that are impossible to describe” (AH2:28:6).
St. Irenaeus gives us the first attempt to understand the relationship between the Father and the Son when he says: “God has been revealed through the Son, who is in the Father and has the Father in himself” (AH3:6:2). St. Irenaeus also affirms that the Father is himself the creator of the world, in response to the Gnostics. He also teaches that there is only one Christ, even if we give him many names. Therefore, Christ is the Son of God, the Word, Jesus the incarnate God, our Savior and Lord.
B - Gather all in Christ:
The heart of Irenaeus’s teaching about Christ, and indeed the center and heart of all his theological teaching, is his vision of “gathering together all things in Christ.” Clearly, St. Irenaeus borrowed this expression from the Apostle Paul in his letter to the Ephesians (1:10) “for the dispensation of the fullness of time to gather together all things in Christ.” He then extended this idea so much that the idea of “gathering together all things in Christ” encompassed all his teaching about the incarnation, redemption, the coming of the Holy Spirit, the establishment of the Church, and Christ being the head of the body, that is, “the Church.” Irenaeus says that “gathering together all things in Christ” includes taking all things from the beginning and putting them in Christ. God restored the first divine plan for the salvation of the human race that was interrupted by the fall of Adam, and he gathers together all that he made from the beginning in order to renew, to restore, and to reorganize all things in his incarnate Son, who in this way becomes a second Adam for us. And since with the fall of man the whole human race was lost, it was necessary for the Son of God to become man in order to complete the re-creation of the human race: [The creatures that perished had body and blood, because the Lord made man from the dust of the ground, and for his sake all the arrangements of the Lord’s coming took place. Therefore he took to himself body and blood, gathering in himself not another particular man but that first man whom the Father had created, since he sought him who had been lost] (AH5:14:2).
And by this “gathering” of the original man in Christ, not only the first Adam personally but also the entire human race was renewed and restored, as he says: [When he became incarnate and became man, he gathered in himself all the extended history of man, gathering us together and giving us salvation so that we might once again obtain in Christ Jesus what we had lost in Adam, that is, the image and likeness of God] (AH3:18:1).
At the same time the evil consequences of the first Adam's disobedience were destroyed, for he says: "God gathered together in himself the old image of man, in order to kill sin and deprive death of its power and to make man alive" (AH3:18:7). In this way the second Adam renewed the old struggle against Satan and defeated him, for St. Irenaeus says: "If the Lord had come from another father than God the Father, he would not have gathered together in himself that first enmity against the serpent, but because he himself is one, and he himself made us in the beginning and then sent his Son to us in the end, the Lord accomplished this, being born of a woman, he destroyed our enemy and perfected man in the image and likeness of God" (AH5:21:2).
For this reason Christ renewed everything by gathering everything in Himself. St. Irenaeus says: [So what did the Savior bring when He came? Know that He came with all newness, by coming in Himself, and He is the same one who was previously prophesied. For this has been openly declared, that there is newness that will come, to renew man and give him life] (AH4:34:1).
3- Saint Irenaeus’ teaching about the Church:
– St. Irenaeus’s teaching about the Church, or what scholars call “ecclesiology,” is closely linked to his idea of “gathering all things in Christ.” God gathers in Christ not only the past but also the future. Therefore, the Father made him the head of the whole Church in order to continue through her the work of renewal until the end of the world. He says: [Therefore, since there is one God, the Father, as we have already explained, and one Christ, Christ Jesus our Lord, who came by a comprehensive and comprehensive dispensation to gather all things in Himself, and among all these (created) things, man, who is God’s creation; therefore He also gathers man in Himself. The invisible became visible, the incomprehensible became comprehensible, the impassible became suffering; and the Word became man, gathering all things in Himself anew. Thus, as He is the first among the heavenly and spiritual beings that are invisible, so also He is the first among the visible and corporeal things, taking the headship to Himself, and having made Himself the head of the Church, He will draw all things to Himself in due time] (AH3:16:6).
B - Saint Irenaeus was absolutely certain that the teaching of the Apostles continues unchanged in the Church. This teaching, that is, Tradition, is the source and basis of faith, for it is the law of truth, and this law of truth, according to Irenaeus, is the law of baptismal faith, for he says that we receive it in baptism (AH1:9:4). Saint Irenaeus gives a description of the faith of the Church according to the Apostles’ Creed exactly, saying: [Although the Church is spread throughout the world, spread throughout the entire inhabited world from one end to the other, she received from the Apostles and their disciples the faith in one God, the Father Almighty, Creator of heaven and earth and seas and all that is in them; and the faith in one Christ Jesus, who is the Son of God, who became incarnate for our salvation; And faith in the Holy Spirit, who announced the dispensation through the prophets, that is, in the coming of Christ, and his virgin birth, and his sufferings, and his resurrection from the dead, and the bodily ascension of our beloved Lord Jesus Christ into heaven, and his appearing again from heaven in the glory of the Father, to gather all things together in himself, and to raise up the bodies of all men to life, that every knee should bow to Jesus Christ our Lord, and God, and Savior, and King, according to the will of the invisible Father, and that every tongue should confess to him, and that he should execute a just judgment on all, and that he should cast out the spirits of evil, and the angels who transgressed and became adversaries, and the wicked, and the lawbreakers, and the profane, cast all into eternal fire; but in his grace he will give life and the reward of incorruption and eternal glory to those who have kept his commandments and continued in his love, whether from the beginning of their life or from the time of their repentance. This preaching and this faith the Church diligently preserves, though it is scattered throughout the world, as diligently as if it were all in one house; it believes this as if it had one mind, and preaches and teaches as if it had one mouth; and although there are many languages in the world, yet the meaning of the tradition is one and the same. For the same faith is held and handed down by the established churches in Germany, Spain, the Gothic tribes, in the East, in Libya, in Egypt, and in the central regions of the world. But as the sun, being created by God, is one, and is the same throughout the world, so also is the light of the preaching of the truth, which shines on all who desire to obtain the knowledge of the truth. (AH1:10:1-2)
C - St. Irenaeus taught that only the churches founded by the apostles can be relied upon for knowledge of the correct teaching of the faith and knowledge of the truth, because the unbroken succession of bishops in these churches is what guarantees that their teaching is the truth: [Anyone who wants to discern the truth can see the apostolic tradition clearly and manifestly in every church in the whole world. We can count those who were appointed bishops by the apostles in the churches, as well as their successors even to the present day, who never knew or taught anything like the foolish teaching of these (i.e. the Gnostics). If the apostles had known such hidden mysteries that they teach privately and secretly to the perfect, they would certainly have entrusted this teaching to the men whom they appointed as responsible for the churches, for the apostles wanted these men who received authority from them to be blameless and without blemish] (AH3:3:1).
4 - Saint Irenaeus’ teaching on salvation:
The central teaching of St. Irenaeus on redemption is the fact that every human being is in need of redemption and is eligible for redemption. This resulted from the fall of the first parents, which put all their descendants under sin and death, and they lost the image of God. The redemption wrought by the Son of God freed human beings from the slavery of Satan, the slavery of sin, and the slavery of death. Moreover, this redemption gathered all humanity in Christ, and led to the restoration of union with God, to adoption to God, and to likeness to God. However, St. Irenaeus avoids the word deification in this regard, but uses the expressions “adherence to God,” “attachment to God,” and “participation in the glory of God,” but he avoids abolishing the boundaries between God and man as was customary in pagan religions and Gnostic heresies.
St. Irenaeus distinguishes between the image of God and the likeness of God. According to him, man is by nature – with his immaterial spirit – the image of God. As for the “likeness of God,” it is a supernatural resemblance to God that Adam had by the initiative of God’s goodness and grace. This resemblance to God is achieved by the action of God’s Spirit.
The redemption of the individual person is accomplished by the Church and its sacraments in the name of Christ. The sacrament is to nature what the new Adam is to the old. The creature attains perfection through the sacraments. The sacrament is the culmination of the gathering together of all creation in Christ. By baptism man is born again of God. When speaking of baptism, Irenaeus bears witness for the first time in the ancient Christian writings to the baptism of children: [The Son of God came to save all through himself—I say all who are born again through God—babies, children, young men, and old men] (AH2:22:4).
5- Saint Irenaeus’ teaching on the Eucharist:
Saint Irenaeus was so convinced of the real presence of Christ in His body and blood in the Eucharist that he deduced the truth of the resurrection of the human body from the fact that this body was nourished by the body and blood of Christ:
[Therefore, when the mixed cup and the made bread receive the “Word of God,” and the Eucharist becomes the body and blood of Christ, which increases and sustains our body, how can they assert that the body is not prepared to receive the gift of God, which is eternal life; this body of ours which is nourished by the body and blood of the Lord, and of which it is a member; that body which is nourished by the cup which is His blood, and receives an increase from the bread which is His body. And as the branch taken from the vine when it is planted in its season, or as the grain of wheat which falls into the earth and dies and decays, rises with increase in many kinds by the power of the Spirit of God, and becomes the Eucharist which is the body and blood of Christ, so our bodies also, being nourished by it, when they are placed in the earth, and decay and die, will rise in their appointed time] (AH5:2:3). And in another place he says:
[And how do they say that the body becomes corruptible and does not share in life, since it is nourished by the body and blood of the Lord? Either they change their mind, or they cease to offer the offerings I have mentioned. As for us, our teaching is in agreement with the Eucharist, and the Eucharist in its turn confirms our teaching. We offer to Him the offerings that are His, and thus we manifest our fellowship and union, and acknowledge the resurrection of body and soul. For just as the bread of the earth, when it receives the gift of God, is no longer ordinary bread, but a Eucharist composed of two elements, one earthly and one heavenly, so also our bodies, when they receive the Eucharist, are no longer subject to corruption, but have the hope of eternal resurrection.] (AH4:18:5).
From these words it is clear that Saint Irenaeus believes that the bread and wine are sanctified by the prayer of invocation of the Spirit. He also believes that the Eucharist is a sacrifice, because he sees in it the new sacrifice prophesied by Malachi:
[And when he (the Lord) gave directions to his disciples to offer the firstfruits of all created things that belong to him - not as one who needed them, but so that they themselves would not be unfruitful, nor ungrateful - therefore he took that created thing, that is, the bread, and gave thanks, and said: “This is my body” and likewise the cup, which is a part of that creation to which we belong, this wine he confessed to be his blood, and taught about the new sacrifice of the new covenant, which the church offers to God in all the world as it received it from the apostles, and it is an offering to him who gives us the firstfruits of his gifts of the new covenant as a means of survival and existence, that offering which Malachi, one of the twelve prophets, foretold, saying: “I have no pleasure in you, says the Lord of hosts, nor will I accept an offering from your hand. “For from the rising of the sun even to its setting my name is great among the nations, and in every place incense and pure offerings shall be offered to my name, for my name shall be great among the nations,” says the Lord of hosts (the Lord Almighty)” making it clearer in these words that the ancient people (the Jews) will cease to offer sacrifices to God, but that sacrifices will be offered to him (God) everywhere, pure sacrifices, and that his name will be magnified among the nations] (AH41:17:5).
6 - His teaching about man:
St. Irenaeus adopts the idea of man being composed of a body and a soul that receives the spirit: he says: [All acknowledge that we are composed of a body taken from the earth, and a soul that receives the spirit from God] (AH3:22:1).
Therefore, a human body animated only by a natural (or animal) soul is not a complete man. St. Irenaeus, like the Apostle Paul, always seems to regard the “spirit” that completes and crowns human nature as the Spirit of God himself. Christ promised this Spirit as a gift to his apostles and believers, and the Apostle Paul tells Christians again and again that they bear this Spirit within them as in a temple. Irenaeus’s teaching about man is clear from the passage in which he describes the complete man created in the image of God:
[That by the hands of the Father, that is, by the Son and the Spirit, man was created—and not merely a part of man—created after the likeness of God. For the soul and the spirit are certainly a part of man, and certainly not man; for the perfect man is formed by the mixture and union of the soul, having received the Spirit of the Father, and the mixture of that fleshly nature, which was also formed according to the image of God. For if one excludes the body from the work of God’s hands, and considers the spirit alone as its work, this is not a spiritual man, but the spirit of man or the spirit of God. But when the spirit, which is merged with the soul, is united with the body, man becomes spiritual and perfect because of the outpouring of the Spirit upon him, and this is the “man” who was made in the image and likeness of God. But if the soul is without spirit, then he who is thus is in truth of an animal nature, and, remaining fleshly, will be an imperfect being, even if he has the image of God in his constitution, but does not obtain the likeness by the Spirit; and therefore he is imperfect. Therefore, if one excludes the form and sets the body aside, he cannot then understand this being as a man, as I said before, or as something other than a man. For that body which has been formed is not a complete man in itself, but a human body and a part of a man, and so the soul itself, if considered in itself only (i.e. without the body), is not a man but the soul of a man and a part of a man. So also the spirit is not a man, for it is called spirit, and is not called man; but the mingling and union of the three together forms a complete man.] (AH5:6:1).
And in another place in the same book he says: [So, there are three elements - as I have previously explained - that make up the “perfect” human being, and they are: the body, the soul, and the spirit. (3)One of these three is that which is preserved and formed, and that is the spirit. The other element is that which is united and formed, and that is the body; and the third element is between these two, and that is the soul, which sometimes, when it follows the spirit, is elevated by the spirit, but at other times, if it turns toward the flesh, it falls into carnal lusts. So those people who have nothing to save and form for eternal life and have no unity are “flesh and blood.”(4)And so they will be called “flesh and blood.” Because these are the ones who do not have the Spirit of God in themselves, and the Lord spoke of such as these as dead when He said, “Let the dead bury their dead” (Luke 10:60), because they do not have the spirit that gives life to man” (AH5:9:1).
It is understood from St. Irenaeus’s teaching about man that the reception and preservation of the third element – the soul – on which the essential perfection of man depends is conditional on man’s will and his spiritual and moral conduct. Even the eternal existence of the soul depends on its conduct here on earth, because the soul is not immortal by nature. Its immortality is connected with spiritual and moral growth. The soul can become immortal if it is grateful to its Creator. In this regard, St. Irenaeus says:
[For just as the heavens above us, that is, the firmament, the sun, the moon, and the rest of the stars, and all their splendor, though they had no previous existence, were called into existence, and continue to exist for a long period of time according to the will of God, so also every man who thinks thus concerning souls and spirits, and indeed concerning all creatures, will not be misled in his reasoning at all. For all things that were created had a beginning when they were made, and continue to exist as long as God wills them to exist and continue… For life does not originate from us or from our own nature, but is given to us according to the grace of God. Therefore the man who preserves the life given to him and is grateful to his Creator who gave it to him will receive length of days forever and ever. But he who rejects the gift and proves himself ungrateful to his Creator—for this man is a creature—and does not appreciate and know Him who gave him life, this man deprives himself of the privilege of perpetuating it forever and ever.] (AH2:34:3)
It is noteworthy, as Massuet says, (5) St. Irenaeus's statement, "Therefore this man deprives himself of the privilege of permanence forever," should be understood in agreement with St. Irenaeus' repeated assertions that the wicked will be miserable forever. This statement, then, does not refer to the total annihilation of the wicked but to the deprivation of happiness.
(1) Quasten, Patrology Vol. I, 294.
(2) He meant the Gnostics who believed in the existence of several births of the ages and times.
(3) Saint Irenaeus stresses that The perfect human being It consists of body, soul and spirit, and the soul, according to him, is what the soul receives from God.
(4) 1 Corinthians 5:15, and here Saint Irenaeus responds to the Gnostics who called for the body not to be saved because it is evil in itself by their incorrect interpretation of this verse: “For flesh and blood will not inherit the kingdom of heaven.”
(5) This Massuet note was made by the publisher of Volume 1 of the ANF collection containing St. Irenaeus’s Against Heresies. The note appears in the margin of page 412 of Volume 1, commenting on the above-quoted phrase from Book 2 of Against Heresies (AH2:34:3).