In the intellectual and theological ferment of the early third century, Caius of Rome appears as a learned but elusive figure—an ecclesiastical author of high repute whose pen was sharpened against the excesses of Montanism and the speculative visions of Chiliasm. Though his surviving words are few, preserved only in fragments, they place him in the company of Irenaeus and Hippolytus as part of a distinctly Western tradition of Greek-writing theologians, whose works bridged the thought-world of the East and the practical life of the Roman church. His testimony concerning the resting places of Peter and Paul offers one of the earliest tangible glimpses into the sacred topography of Rome, while his polemic against heretical apocalypticism reflects the sober realism of a church navigating the tensions between spiritual fervor and doctrinal order.
Historical Sources and Identity
Caius is known to us through brief but significant notices in Eusebius (Hist. Eccl. II. 25; III. 28, 31; VI. 20), Jerome (De Viris Illustribus 59), Theodoret (Haereticarum Fabularum Compendium II. 3; III. 2), and Photius (Bibliotheca Cod. 48). He may also be the Caius mentioned in the Martyrdom of Polycarp (c. 22) as a pupil or friend of Irenaeus.
Scholars such as Routh, Bunsen, Caspari, Harnack, and Salmon have gathered the scattered fragments of his life and writings, noting his probable role as a presbyter in the Roman church during the episcopate of Zephyrinus (c. 199–217). From his name and the fact that he omitted Hebrews from the Pauline corpus, it is inferred that he was of Roman or at least Western origin. Eusebius calls him a “very learned churchman” and cites four excerpts from his disputation with Proclus, leader of one Montanist faction.
The Disputation with Proclus
The recorded exchanges between Caius and Proclus provide two memorable contributions to church history. First, Caius notes that Philip the Evangelist and his four prophetic daughters were buried at Hierapolis in Phrygia. Second, he bears witness to the existence of the “trophies” of Peter and Paul—the monuments honoring the apostles—situated respectively on the Vatican Hill and along the Ostian Way. These attestations are among the earliest extra-biblical confirmations of apostolic veneration in Rome.
Opposition to Montanism and Chiliasm
Caius’s theological stance was shaped by his opposition to Montanist enthusiasm and to the Chiliastic speculations then circulating under the name of Cerinthus. While rejecting the excesses of apocalyptic imagination, he did not—as some have misconstrued—deny the Johannine authorship of the Apocalypse. Rather, his critique likely targeted spurious revelations attributed to heretics. This position aligned him with the Roman church’s canon, which recognized thirteen Pauline epistles (excluding Hebrews) and accepted the Apocalypse of John.
Confusion with Hippolytus
Photius, relying on a marginal note in a manuscript, described Caius as a presbyter of Rome under Victor and Zephyrinus and claimed he was “bishop of the Gentiles” (episkopos ethnōn). He attributed to him a work On the Universe and The Labyrinth, though with hesitation. These attributions appear to stem from a confusion between Caius and Hippolytus—an error perpetuated by later critics. Although they shared a similar timeframe, city, and ecclesiastical title, their theological emphases diverged: Hippolytus was not an opponent of Chiliasm, whereas Caius wrote directly against it.
The Muratorian Fragment
The celebrated Muratorian fragment on the New Testament canon was once ascribed to Caius by its discoverer, Ludovico Antonio Muratori (1740), and by several later writers. Modern scholarship, however, dates the fragment to around A.D. 170—earlier than Caius—and regards it as originally composed in Latin, though possibly translated from Greek. It is, as far as is known, the oldest extant Latin ecclesiastical document from Rome and of immense importance for the history of the canon. While some hold that it originated within the Roman church, others, such as Caspari, suggest it was the work of an African Christian residing in Rome, drawing upon an earlier Greek source.
Legacy
Caius’s enduring significance rests less on the breadth of his surviving works than on the precision of his witness. His opposition to Montanism and to exaggerated apocalyptic speculation reveals the measured temper of early Roman orthodoxy. His mention of the apostolic monuments grounds the spiritual authority of Peter and Paul in the tangible soil of Rome, anchoring memory and devotion in place as well as in doctrine. Though often overshadowed by Hippolytus, Caius’s fragments preserve the voice of a presbyter-scholar whose blend of historical awareness and theological restraint served the stability of the early third-century church.
