There is an entry in the Common Worship Calendar for 28 June which reads ‘Irenaeus, Bishop of Lyon, Teacher of the Faith, c.200’. The date of c.200 shows that this feast-day honours one of the very early bishops of the church.

We don’t know the exact dates of Irenaeus’s life and we have very few biographical details, but his surviving writings justify the description of him as ‘the first great Catholic theologian’ (Oxford Dictionary of the Christian Church).  It’s important to remember that he was active at a time when Christianity was still not a publicly practised religion: it did not – and could not – go public until the Roman Emperor Constantine made space for it by his Edict of Milan in 312, which allowed all religions to be openly practised alongside the long-established Roman cults. Constantine tended to favour Christianity, but it was not until the end of the fourth century, under the Emperor Theodosius, that Christianity became the state religion of the Roman Empire. Furthermore, Irenaeus was thinking, teaching and writing at a time when the doctrines of Christianity, the understanding of the nature of Jesus, the concept of the Trinity, and ideas of what was orthodox and what was not, were still being worked out. And in those very early centuries there was not even a fixed Christian Bible, or even an agreed group of texts that would go on to become the books of the New Testament. Although all four gospels existed, other texts were also in circulation, some of which were not, in the end, included in the New Testament; and even the gospels were often not considered together as complementary texts, as we do today. Different groups fastened on one gospel as the definitive text and downplayed the others, and while some groups paid close attention to written texts (not always just one ones we use today), others paid scant attention to what was written. There were also various sects and philosophical systems which had some points of similarity with Christianity, so much so that some of these groups claimed to be Christians – although many Christians (Irenaeus among them) thought they were not. This was the difficult context in which Irenaeus provided formative leadership, helping to lay important foundations for future theologians.

In a world that predated the formation of the Bible, Irenaeus nevertheless argued for the primacy of the four gospels of Matthew, Mark, Luke and John as texts of complementary importance; and in his writings he also made extensive use of the Jewish Scriptures (which became our Old Testament), showing how they related to the new world of Christianity. So he was a major contributor to the development of the Bible as we know it. He also contributed to the challenging debates on nature of Jesus, insisting on the unity of God the Father and God the Son, whilst at the same time giving positive value to Jesus’s human nature on earth.

It is thought that Irenaeus was born in Smyrna (modern Izmir) in Asia Minor and so was a native Greek speaker, the language in which his works were originally written. But he studied in Rome and then became a presbyter in Lyon, one of the great Roman cities. He was in Rome on ecclesiastical business c.177, when there was a local persecution of Christians, in which Bishop Pothinus was martyred. Irenaeus succeeded him as bishop on his return in 178, We do not know how he died, or precisely when, but his dates are usually given as c.130-c. 200.

Joyce Hill