A native of Asia Minor, Irenaeus was bishop of a Christian community in Roman Gaul during the last quarter of the second century. As such, his day-to-day duties were likely those of a pastor and missionary. And yet he stands today as one of the seminal figures in pre-Nicene Christian theology. There was, to be sure, a clear connection between his theological work and his pastoral responsibilities. In his time, Gnostics, Marcionites, and others were preaching that the physical world, including the human body, was created not by God, the Father of Jesus, but by an inferior spiritual being. As such, they said, the flesh is neither capable nor worthy of being redeemed.
Against these sects, Irenaeus wrote his well-known Against Heresies (AH). Here he used the Bible to show that the body is the handiwork of the true God, modeled after the image of his Son, who was to become incarnate. Accordingly, Irenaeus maintained, the God who created the first human bodies and causes bodies to live even now will resurrect the bodies of believers unto eternal life, even as he resurrected the body of his incarnate Son.
Irenaeus’s theology of the body is profound and, given confusion even among Christians about the inherent dignity of the body, more needful today than ever. Yet it is not the totality of his theological anthropology. Irenaeus also developed sophisticated teachings about the soul’s nature and functions — teachings that intersected with his day-to-day ministry. What, then, might be the contemporary relevance of his teachings about the soul?
The Soul’s Nature
In AH 2.13.3-4, Irenaeus reveals something of his thinking on the soul’s nature by contrasting the mind, which he regarded as the chief part of the soul, to God:
For the Father of All is far removed from the dispositions and passions of the human mind, and simple, and non-composite … since he is all mind, and all understanding, and all thought …Yet, he is even beyond these, and on account of this, ineffable. He may well and rightly be called mind that comprehends all things, but not like a human mind … for the Father of all things is in no way similar to humanity’s littleness.
Here Irenaeus engages philosophical theology in light of his commitment to the biblical distinction between God the Creator and human beings, whom God creates. Many ancient philosophers thought the soul had a natural kinship to the divine. Using a title for God that is both biblical (Eph. 4:6) and philosophical (Plato, Timaeus 28c), Irenaeus challenges that perception of a natural relationship. According to Irenaeus, the Father of All is “simple” and “non-composite.” Both terms essentially mean “not composed of parts,” which is the philosophical equivalent of saying that God is not material, because any material entity can, in theory, be separated into smaller and smaller pieces.
It may not be obvious that saying God is simple, and implicitly then, immaterial, should mean that God’s nature is “in no way similar” to the nature of the human soul. The cogency of Irenaeus’s contrast only becomes clear when one realizes that Irenaeus believed that the soul is physical. Indeed, in AH 5.7.1, Irenaeus contrasts the “simple” and divine Holy Spirit with human souls, which are not incorporeal in an unqualified sense, but only “incorporeal in so far as they are compared to mortal bodies.”
In other words, the soul is a refined substance, imperceptible to the senses, and yet mixed and united with the body even to the extent that it preserves the shape of the human body after death, as Irenaeus infers from the story of Lazarus and the Rich Man in Luke 19 (AH 2.34.1). This view of the soul’s corporeality was a well-known tenet of Stoic philosophy. Irenaeus, it appears, is using philosophy to develop a view of the nature of the soul as corporeal, and thus, as distinct from the simple nature of the Creator.
The Soul’s Functions
Along with the soul’s nature, Irenaeus also had a sophisticated account of the soul’s functions. Here we should consider his views of how the soul “knows,” which was, in antiquity, seen as a function of the soul rather than the brain. Philosophers in Irenaeus’s era had sophisticated accounts of the process by which the soul arrives at knowledge. First, the soul “perceives” external phenomena through the bodily organs of sense perception — the eyes, ears, and so on. Then, the soul evaluates the “impressions” and “memories” that these sense perceptions leave within the soul. As a result of these evaluations, the soul may form a “belief” — pistis, the biblical word for “faith” — “judgment,” “conception,” or “apprehension” of a given aspect of reality.
Surveying Irenaeus’s corpus, one often encounters these philosophical technical terms. Indeed, Irenaeus uses these terms even in specific, complex accounts of how the soul “knows” (for example, AH 2.33.1-5, 4.39.1). Thus, Irenaeus appears to be familiar with philosophical epistemology, which he uses even to explain how human beings know God through Christ.
Though the simple God is by nature “inapprehensible to the mind” (4.19.2), which, as corporeal, is in no way similar to God, in the incarnation of his Son, God becomes “present with his handiwork, saving it, and perceptible to it” (4.20.4). Here perceptible alludes to sense perception and the broader process of sense-based knowing, by which we can, according to Irenaeus, “learn the things of God by seeing Jesus, our Teacher, and perceiving his voice with our ears” (5.1.1).
With statements such as these, Irenaeus shows that just as he holds a sophisticated, philosophically informed view of how the soul’s nature differs from its Creator’s, so too he has a philosophically informed explanation for how the soul can come to know its Creator through the incarnate Son of God. The soul, then, is not an afterthought for Irenaeus. Even though we usually think of Irenaeus as a theologian of the body, his theology of the soul cannot be underestimated.
The Soul in Christian Ministry
Irenaeus’s reflections on the soul were not merely philosophical. They intersected with his everyday ministry. In AH 3.4.2, he writes that the people to whom he ministers in Roman Gaul.
Believe in Christ, [and] … have believed the Faith. They are Barbarians with respect to their language, but as regards thought and practices and conduct they are most wise and pleasing to God on account of the faith, conducting themselves as they do in all righteousness and purity and wisdom. If anyone were to tell them about the fictions of the heretics, they would immediately stop up their ears and flee far away, tolerating not even to hear such blasphemous discourse.
Indeed, he continues, “they do not admit even into their minds’ conception any heretics’ monstrous assertions.”
In this passage, Irenaeus describes how the “Barbarians” respond to the heresy that the Creator of the world is not the true God. In ancient Rome, Barbarian referred to a diverse range of people groups. These groups shared little except being, in the opinion of most Greeks and Romans, inferior. It is possible, if not likely, that Irenaeus shared some of these prejudices. But if so, that makes his description of the Barbarians even more striking.
According to Irenaeus, the Barbarians have an unrivaled fidelity. Their conduct is above reproach, and their lives are characterized by “righteousness,” “purity,” and “wisdom.” How, one might ask, could a Greek like Irenaeus have explained the virtue of Barbarians such as these? The answer, his writing suggests, lies in their souls. They “believe” the gospel that they hear through their ears, and they stop up their sense-perceptive organs whenever they perceive heresy. Thus, they avoid forming false “conceptions” within their minds. It is “because of their faith”—and here the meaning of faith includes the epistemic sense of “belief” — that they lead a virtuous life in fidelity to God.
In this passage, Irenaeus’ use of epistemological technical terms like belief and conception reveals that he presumes the souls of the Barbarians are equipped with mental faculties that allow them to receive and be transformed by the preached gospel of Jesus Christ. Thus, they are able to join the Christian community, in which they spiritually flourish as might any believing Greek or Roman. Irenaeus’s views of the soul, then, play a key role in his rationale for ethnic inclusivity in the Christian church. This rationale undoubtedly guided his day-to-day ministry as he, a Greek, ministered to the Barbarians in Gaul.
A Gospel for All People
Irenaeus’s views of the soul are surely not standard throughout Christian history. It is common in later generations, for example, to think of the soul as incorporeal or immaterial. Moreover, some later Christians would contend that the souls of certain peoples are less able to receive the gospel — a position that they used to oppress and marginalize those peoples.
Irenaeus’s teachings about the soul represent potentially useful and liberating alternatives to these perspectives. First, his understanding of the soul as semi-corporeal and that knowledge is dependent upon sense perception is amenable to modern cognitive science, which correlates mental states to physical states of the brain. Moreover, his affirmations of all people’s ability to hear the gospel, believe it, and be transformed by it are likewise important for — and confirmed by — global Christian communities. The passage cited above, along with others wherein he describes the Church as an ethnically diverse body of believers who share a single soul and single faith (1.10.1-2), represent an important ancient attestation to the truth that the gospel is meant for people of all races, tribes, and tongues.
Grayden McCashen, Ph.D. is a Guest Writer. He has taught for Candler School of Theology at Emory University, Spelman College, and, currently, Columbia Theological Seminary. He is a 2024-2025 Visitor for the History of Philosophy Forum at Notre Dame. His writing has appeared in The Journal of Theological Studies, Vigiliae Christianae, The Journal for the Study of Judaism, and The Journal of Ecclesiastical History.