Note: As a service to fellow researchers, I am going to post critical biographies of the church fathers I examined in my book The Trinitarian Testimony of the Spirit. These biographical overviews were included in my original dissertation but were cut from the published version. Original footnotes are included as endnotes below; in conjunction with the essential bibliographies I have posted, this should help those looking to get into the literature on the early church fathers. I have been struck by how many published sources read the primary sources with a fairly uncritical lens; in these summaries, like any good historian, refuse to take primary sources at face value.
Irenaeus of Lyons: A Critical Biography
As influential as Irenaeus’s writings have been, much of his life remains shrouded in mystery, with his writings providing little assistance in reconstructing his biography. As with Justin, most of our knowledge concerning the life of Irenaeus comes from Eusebius. Our first clue for establishing a chronology of Irenaeus’s life concerns his relationship with Polycarp, the bishop of Smyrna who was martyred ca. 156 CE. In a letter to Florinus, preserved by Eusebius, Irenaeus describes how when he was a boy he listened eagerly to Polycarp’s teaching, a point to which he also alludes in Against Heresies. As a result, scholars place the date of Irenaeus’s birth between 130 and 140 CE, with Asia Minor, perhaps more specifically the city of Smyrna, as the most plausible location for his birth.
At some point, Irenaeus moved west. Irenaeus almost certainly passed through Rome, and likely spent a considerable amount of time there. In any event, he eventually arrived in Lugdunum (modern-day Lyons in France), and it is in this city that Irenaeus became first a presbyter and then a bishop. In Irenaeus’s time, Lyons was the largest city north of the Alps as well as the center of both religious and economic activity in the province of Gaul. Some time around 177 CE, an intense persecution broke out in Lyons and nearby Vienne, and Eusebius preserves a letter from these Gallic churches to the churches in Asia Minor providing details of the martyrdoms that occurred at that time. At some point during the persecution, Irenaeus was sent to Rome bearing a letter to Eleutherus, the bishop of Rome ca. 174–189 CE, identifying him as a presbyter of the Gallic church. The aged bishop Pothinus was also martyred during the persecution, thus opening the door for Irenaeus’s presumed elevation to the episcopacy ca. 180 CE.
Our best insight into Irenaeus’s ministry in Gaul comes from the aforementioned letter from the churches of Vienne and Lyons to the churches of Asia and Phrygia, from which we can glimpse “a remarkable Christian community, proud of those members who endured appalling torments, but prepared to acknowledge that some had weakened and, what was even more unusual in the early Church, prepared to forgive them.” The fact that the letter was written in Greek and addressed to these Eastern churches suggests that the Christians in Lyons and Vienne were Greek-speakers with roots from Asia Minor, a hypothesis that fits well with known migration patterns from Asia to Gaul during this period. The presence of Latin names among the list of martyrs suggests a significant Roman presence among the Greek-speaking majority in a church that likely drew members from across all of Lyons’s social classes. Scholars are divided as to whether any form of Gnosticism was present in Gaul during the time of Irenaeus’s episcopate, but the evidence appears to be on the side of there being at least some Gnostic activity, which would explain both the extent of Irenaeus’s familiarity with their beliefs and the vehemence of his polemic.
During his episcopate in Lyons, Irenaeus was actively engaged in the church’s missionary endeavors to the Celts in Gaul. Despite bemoaning the lack of what he considered to be high culture in Gaul, Irenaeus was nevertheless motivated by his beliefs in the universality of the church and in the ability of the gospel to be truly accepted even among the so-called barbarians. The successfulness of Irenaeus’s mission to the Gauls, Gregory of Tours’s sixth-century embellishments notwithstanding, is something of an open question, though as mentioned above, there appears to have been a small Celtic contingent within the church at Lyons.
Irenaeus extensively involved himself in the theological disputes affecting Rome in the late second century, as evidenced by the numerous examples of his letters to Roman church leaders that are quoted or referenced by Eusebius. Perhaps the most significant of these is a letter to Victor, who was bishop of Rome in approximately the last decade of the second century, concerning the Quartodeciman controversy. In response to Victor’s attempt to excommunicate the Christians from the churches of Asia Minor on account of their difference in dating the celebration of Easter, Irenaeus pressed for peace between the churches out of respect for the ancient tradition followed by the Eastern churches. Eusebius thus ends his account of Irenaeus’s life; although later accounts suggest that Irenaeus was himself martyred, this cannot be historically corroborated. Regarding the date of Irenaeus’s death, Minns is correct to point out that “there is no evidence that Irenaeus lived beyond the reign of Victor,” whose tenure as bishop of Rome ended ca. 198 CE.
Perhaps the most important issue concerning Irenaeus’s life for this study is the extent of Irenaeus’s knowledge of other early Christian writings. With respect to Justin Martyr, J. Armitage Robinson has convincingly demonstrated Irenaeus’s knowledge of and dependence on Justin, suggesting that Irenaeus had physical copies of Justin’s writings in his possession when composing his own works. Not only this, but the evidence places Irenaeus in Rome at the same time that Justin was at the height of his career in that same city, making it highly unlikely that the two men did not have at least some degree of personal acquaintance. Indeed, in his own writings Irenaeus speaks highly of Justin and names him as a source for his heresiological writings. As such, in this chapter we will assume Irenaeus’s direct use of Justin’s writings, though the extent to which Irenaeus may have been influenced by Justin’s view of the Trinitarian testimony of the Spirit will be explored and validated later in this chapter. With respect to his use of the New Testament, as fitting his broader project of showing the continuity between Old and New Testaments Irenaeus quotes extensively from the vast majority of the New Testament writings.
 For an overview of Irenaeus’s life, see F. R. M. Hitchcock, Irenaeus of Lugdunum: A Study of His Teaching (Cambridge: Cambridge University Press, 1914), 1–18; Morton S. Enslin, “Irenaeus: Mostly Prolegomena,” HTR 40 (1947): 137–65; Pierre Nautin, Lettres et écrivains chrétiens: Des IIe et IIIe siècles (Paris: Cerf, 1961), 92–104; Robert M. Grant, Irenaeus of Lyons, ECF (London: Routledge, 1997), 1–10; Eric Osborn, Irenaeus of Lyons (Cambridge: Cambridge University Press, 2001), 1–7; Denis Minns, Irenaeus: An Introduction (London: T&T Clark, 2010), 1–13; Paul Parvis, “Who Was Irenaeus? An Introduction to the Man and His Work,” in Irenaeus: Life, Scripture, Legacy, ed. Paul Foster and Sara Parvis (Minneapolis: Fortress, 2012), 13–24; John Behr, Irenaeus of Lyons: Identifying Christianity, Christian Theology in Context (Oxford: Oxford University Press, 2013), 66–71; Jackson Lashier, Irenaeus on the Trinity, VCSup 127 (Leiden: Brill, 2014), 18–41.
 On the dating of the martyrdom of Polycarp, see Sara Parvis, “The Martyrdom of Polycarp,” in The Writings of the Apostolic Fathers, ed. Paul Foster (London: T&T Clark, 2007), 127–32.
 Hist. eccl. 5.20 (SC 41:60–63).
 Haer. 3.3.4 (SC 211:38–44). The anonymous elder that Irenaeus introduces in Haer. 4.27.1 (SC 100:728) may in fact be Polycarp; so Charles E. Hill, From the Lost Teaching of Polycarp: Identifying Irenaeus’ Apostolic Presbyter and the Author of Ad Diognetum, WUNT 186 (Tübingen: Mohr Siebeck, 2006), 7–94; idem, “The Man Who Needed No Introduction: A Response to Sebastian Moll,” in Irenaeus: Life, Scripture, Legacy, ed. Sara Parvis and Paul Foster (Minneapolis: Fortress, 2012), 95–104. For more on the relationship between Irenaeus and Polycarp, see Behr, Irenaeus of Lyons, 57–66; Hill, Lost Teaching, 72–80.
 Osborn (Irenaeus of Lyons, 2) and Lashier (Irenaeus on the Trinity, 18) broadly suggest the years 130–140; Behr (Irenaeus of Lyons, 67) locates Irenaeus’s birth closer to 130 CE, whereas Grant (Irenaeus of Lyons, 2) locates it closer to 140 CE. The other factor to consider in this is that because we know Irenaeus carried a letter from Gaul to Rome in 177 CE, when he served as a presbyter in the church of Lyons, it is unlikely that he could have been born after 140 CE and still have been old enough for the presbyterate; cf. Enslin, “Irenaeus,” 145.
 Parvis (“Who Was Irenaeus?,” 15) notes that whether or not Irenaeus was himself from Smyrna, “It is in any event clear that Irenaeus was from the East. He thought and wrote in Greek and has links both personal and theological with Asia Minor.” Cf. Lashier, Irenaeus on the Trinity, 20–21.
 Nautin (Lettres, 93) suggests that Irenaeus came to Rome in order to find work as a rhetorician. A lengthy stay in Rome would also explain Irenaeus’s close ties with that city, as revealed in his letters and later emissary trip. The Moscow Manuscript of the Martyrdom of Polycarp places Irenaeus in Rome at the time of Polycarp’s death; cf. Osborn, Irenaeus of Lyons, 3.
 Hitchcock (Irenaeus of Lugdunum, 3) hypothesizes that Irenaeus fled to Gaul during the persecution of Marcus Aurelius, under which Justin was martyred.
 Hist. eccl. 5.4–5 (SC 41:27–31). Julius Caesar conquered Gaul in 52 BCE, and shortly thereafter in 43 BCE the Romans established Lugdunum on a hilltop overlooking where the Rhône and Saône rivers come together. On the founding of these towns, see further Behr, Irenaeus of Lyons, 17–18. On the close relationship between the churches of Gaul and Asia Minor (including Smyrna), see Hitchcock, Irenaeus of Lugdunum, 3–4.
 Parvis, “Who Was Irenaeus?,” 15; see further Enslin, “Irenaeus,” 155–57; Behr, Irenaeus of Lyons, 16–21.
 This dating is an important fixed point in a chronology of Irenaeus’s life, as Eusebius gives the year of the persecution as the seventeenth year of Antoninus Verus (that is, Aurelius Verus, who co-reigned with Marcus Aurelius).
 Hist. eccl. 5.1 (SC 41:6–23). Though this cannot be proven, it is at least possible that Irenaeus wrote this letter himself; so Nautin, Lettres, 54–61. On the significance of this letter, see Enslin, “Irenaeus,” 148–49.
 This letter is preserved in Hist. eccl. 5.4 (SC 41:27–28); cf. Hitchcock, Irenaeus of Lugdunum, 5–7. As Minns (Irenaeus, 2) observes, “it might seem odd that a high official in the Christian community should not only be at liberty while other members of that community were imprisoned, but even be able to travel to Rome on the business of the community.” Nautin (Lettres, 94) tries to solve the mystery of Irenaeus’s survival by suggesting that Irenaeus was at the time of the persecution bishop of Vienne and therefore largely unknown to local authorities. It was only upon the death of Pothinus, according to this reconstruction, that Irenaeus was consecrated bishop over Lyons as well.
 Hist. eccl. 5.5 (SC 41:31). Irenaeus, it should be noted, never identifies himself as a bishop, and to compound the problem there are difficulties in distinguishing between the offices of bishop and presbyter at this point in early Christian history; cf. Minns, Irenaeus, 2; Grant, Irenaeus of Lyons, 6. On the question of who consecrated Irenaeus, see Hitchcock, Irenaeus of Lugdunum, 8.
 Minns, Irenaeus, 3–4. Minns (Irenaeus, 4–5) goes on to find evidence of a critique of the Roman church’s developing hierarchy, which is intriguing in light of Irenaeus’s later emphasis on the importance of the episcopacy.
 Minns, Irenaeus, 3; Grant, Irenaeus of Lyons, 4; Behr, Irenaeus of Lyons, 19.
 Osborn, Irenaeus of Lyons, 2.
 Donovan, One Right Reading?, 32–33; Lashier, Irenaeus on the Trinity, 31. Irenaeus also refers to the presence of the followers of Marcus, a disciple of Valentinus, in his own area; cf. Haer. 1.13.7 (SC 264:204).
 Haer. 1.pref.3 (SC 264:24).
 Haer. 3.4.2 (SC 211:46–48); cf. Grant, Irenaeus of Lyons, 4–5.
 As Grant (Irenaeus of Lyons, 5) points out, the letter from the churches of Lyons and Vienne in ca. 177 CE does not include any Celtic names, and so at least as of this time “the Celtic population remained resolutely non-Christian.” The early church at Lyons disappears from historical view after the city was sacked ca. 197 CE following Septimus Severus’s defeat of Clodius Albinus; cf. Minns, Irenaeus, 5.
 Hist. eccl. 5.20, 5.24 (SC 41:60–63, 69–71). On these letters and their historical context, see further Enslin, “Irenaeus,” 151–53.
 On the nature of the Christian communities in Rome during this period, see Behr, Irenaeus of Lyons, 21–47; Peter Lampe, From Paul to Valentinus: Christians at Rome in the First Two Centuries, trans. Michael Steinhauser, ed. Marshall D. Johnson (Minneapolis: Fortress, 2003), noting especially 292–318 on the Roman Valentinians. For text and introduction to this letter, see Nautin, Lettres, 74–85.
 Hist. eccl. 5.24 (SC 41:69–71); Eusebius takes the opportunity to note that Irenaeus’s name comes from the Greek word for “peace.” Cf. Hitchcock, Irenaeus of Lugdunum, 11–12; Minns, Irenaeus, 2–3; Grant, Irenaeus of Lyons, 8–10.
 This tradition is, at the earliest, attested by Jerome (ca. 342–420 CE), with the first full account of Irenaeus’s martyrdom provided by Gregory of Tours (ca. 540–594 CE); cf. Behr, Irenaeus of Lyons, 14 n. 4; Hitchcock, Irenaeus of Lugdunum, 17–18.
 Minns, Irenaeus, 3. Jerome’s account suggests that Irenaeus died in 202 or 203 CE during the persecution of Septimus Severus, but there are good reasons for doubting this tradition; cf. Osborn, Irenaeus of Lyons, 2.
 J. Armitage Robinson, intro. and trans., The Demonstration of the Apostolic Preaching (London: SPCK, 1920), 6–14. See further Lashier, Irenaeus on the Trinity, 22–26.
 It is quite plausible that Irenaeus was even one of Justin’s students; see further Michael Slusser, “How Much Did Irenaeus Learn from Justin?” StPatr 40 (2006): 515–20.
 Haer. 1.28.1, 4.6.2, 5.26.2 (SC 264:356; SC 100:440; SC 153:334).
 By one count, Irenaeus quotes 1,075 passages from the New Testament, including all its books except Philemon, 2 Peter, 3 John, and Jude; cf. Bruce M. Metzger, The Canon of the New Testament: Its Origin, Development, and Significance (Oxford: Clarendon, 1987), 154.