Pope Saint Sixtus I: The Seventh Pope, the Sanctus, and a Name That Means Sixth

The seventh in a series on the popes.

With Alexander I, the sixth pope, the problem was accretion: a name in the earliest source onto which later centuries hung a famous liturgical innovation, a martyr’s death on a Roman road, and a small file of forged letters. With Sixtus I, the seventh Bishop of Rome, the pattern repeats almost verbatim—and the parallels are close enough to be instructive. The man Irenaeus knew only as a name on a list became, in the Liber Pontificalis four centuries later, the pope who instituted the Sanctus, who legislated who could touch sacred vessels, who governed the relations of bishops to the Apostolic See, and who died for the faith. None of those four claims is secure. What is secure is the name itself, the position in the line, and a roughly ten-year reign in the early second century.

This is the seventh entry in my series on the popes, following Peter, Linus, Anacletus, Clement, Evaristus, and Alexander I. If Evaristus is the test case for how Catholic history treats a blank and Alexander the test case for how it treats an accretion, Sixtus is the test case for how it treats a name that became a pun: a pope called the sixth in the list whose Latinized name happens to mean “sixth.”

A Name in the List

The earliest surviving witness to Sixtus is Irenaeus of Lyons, writing his five-book Adversus Haereses (Against Heresies) around AD 180 to refute Gnostic claims to secret apostolic tradition. In Book III, chapter 3, he supplies the earliest extant list of the Roman bishops and uses it as a polemical hinge: the true apostolic teaching is what has been preserved in public, traceable, public-figure succession. Of Sixtus he writes a single clause:

To this Clement there succeeded Evaristus. Alexander followed Evaristus; then, sixth from the apostles, Sixtus was appointed; after him, Telephorus, who was gloriously martyred.

That is the entirety of Irenaeus’s notice.⁠¹ Sixtus is “sixth from the apostles” on a reckoning that counts Linus as the first post-apostolic bishop (so Linus 1, Anacletus 2, Clement 3, Evaristus 4, Alexander 5, Sixtus 6). On the modern Catholic counting that takes Peter himself as the first pope, Sixtus is the seventh. The discrepancy is not contradiction; it is a different starting line. Eusebius, working from Irenaeus a century and a half later, uses the same reckoning: “In the twelfth year of the reign of Adrian, Xystus, having completed the tenth year of his episcopate, was succeeded by Telesphorus, the seventh in succession from the apostles.”⁠² Telesphorus is the seventh; Sixtus, then, is the sixth, on the same accounting.

Eusebius supplies the chronology Irenaeus does not. In Historia Ecclesiastica IV.4 he closes the Alexander entry: “In the third year of the same reign [of Hadrian], Alexander, bishop of Rome, died after holding office ten years. His successor was Xystus.”⁠³ Hadrian’s third year is 119/120 by the usual Caesarean reckoning, which would set the start of Sixtus’s reign there—but Eusebius’s own dates do not quite cohere. His Chronicon (preserved in Jerome’s Latin and in an Armenian translation) gives slightly different figures, and Adolf McGiffert in his NPNF apparatus warns that the Historia Ecclesiastica dates here cannot stand: “the date of his accession given here by Eusebius cannot, however, be correct; for, as Lipsius has shown,” the Roman bishop must have died “at least as early as 126 a.d. (possibly as early as 124), so that his accession took place not later than 116; that is, before the death of Trajan.”⁠⁴

The Liberian Catalogue—the fourth-century list of popes preserved in the Chronograph of 354, on which the Liber Pontificalis would later draw—gives the reign by Roman consular formula: a consulatu Nigri et Aproniani usque Vero III et Ambibulo, “from the consulship of Niger and Apronianus to that of Verus III and Ambibulus.” That is 117 to 126.⁠⁵

The reign is therefore dated only by approximation, and modern reference works settle near c. 115 to c. 125. The 1912 Catholic Encyclopedia notes that “all authorities agree that he reigned about ten years.”⁠⁶ That is the secure core: a man named Sixtus, sixth in Irenaeus’s reckoning and seventh on the Petrine count, who held the see for roughly a decade in the early second century, succeeded Alexander, and was succeeded by Telesphorus. Everything else is later tradition.

There is also the matter of the name. In the oldest documents the spelling is always Xystus—Greek ξυστός, “polished,” “shaved,” sometimes used of a colonnade. The Catholic Encyclopedia preserves the older convention: “in the oldest documents, Xystus is the spelling used for the first three popes of that name.”⁠⁷ The Latinized Sixtus very probably trades on the resonance with sextus, “sixth”: the sixth name on the list bears a name that means “sixth.” The pun is hard to prove and easy to suspect.

Three Ordinances from the Liber Pontificalis

Ask which pope instituted the Sanctus and the conventional answer is Sixtus I. The claim comes from the Liber Pontificalis, the serial papal biography first compiled in Rome around AD 514–535—four centuries after Sixtus’s death. Its entry credits him with three ordinances, summarized by the Catholic Encyclopedia citing Louis Duchesne’s critical edition:

(1) that none but sacred ministers are allowed to touch the sacred vessels; (2) that bishops who have been summoned to the Holy See shall, upon their return, not be received by their diocese except on presenting Apostolic letters; (3) that after the Preface in the Mass the priest shall recite the Sanctus with the people.

That is the Liber Pontificalis in summary, and the three ordinances are the high-water mark of Sixtus’s reputation in later tradition.⁠⁸

The Sanctus attribution is the most famous and the most obviously anachronistic. The triple acclamation “Holy, Holy, Holy, Lord God of hosts”—drawn from Isaiah 6:3 and woven into the Eucharistic anaphora—is so deeply embedded in every early Christian liturgy with surviving witnesses that no fixed date for its “institution” in Rome is recoverable, much less an institution by one named pope around AD 120. The Latin West attests the Sanctus from the mid-fourth century onward in clear textual form, and the parallel Eastern anaphoras have it earlier still; the Liber Pontificalis attribution sits four centuries after Sixtus and reflects a sixth-century compiler’s habit of attaching primitive liturgical practices to early names. As with Alexander I and the holy-water sprinkling, the custom is real and old—but its institution by a specific pope around AD 120 is precisely what the source cannot deliver.

The other two ordinances fare no better. The rule that sacred vessels could be touched only by sacred ministers reflects post-Constantinian clerical discipline; the rule that bishops summoned to Rome must on return present apostolic letters to their flock retrojects an administrative practice of Roman papal jurisdiction that took shape across the fourth and fifth centuries. Each ordinance is internally plausible as later Roman discipline. None is plausible as the act of a Roman bishop in the AD 110s or 120s.

The pattern matches what we have seen with every prior pope in this series. The Liber Pontificalis does not preserve a memory of what these men actually did; it preserves a sixth-century scribe’s sense of what they ought to have done, distributed over their names in even portions. The compilers gave Linus the decree on women’s head coverings, Anacletus the memorial of Peter, Clement the seven regional notaries, Evaristus the seven deacons and the division of Rome into tituli, Alexander the holy water and the Qui pridie—and Sixtus the three ordinances above. Read together, the early entries are a sixth-century atlas of Roman ecclesial practice projected onto a second-century framework.

A Martyr by Inheritance, Not by Evidence

The gravest claim is the martyrdom. The Liber Pontificalis attaches the title Papa et Martyr to Sixtus, and the “Felician Catalogue” of popes (a sixth-century recension of the LP) and the various Western martyrologies repeat it.⁠⁹ But neither Irenaeus, who has space to note the “glorious” martyrdom of Telesphorus immediately after Sixtus, nor Eusebius, who is alert to martyrs, says anything about Sixtus dying for the faith. Eusebius’s silence is conspicuous.

McGiffert puts the modern verdict plainly: “Like most of the other early Roman bishops [Sixtus] is celebrated as a martyr in the martyrologies, but the fact of his martyrdom rests upon a very late and worthless tradition.”⁠¹⁰ Louis Duchesne, the great editor of the Liber Pontificalis, treated the title as a pattern of automatic retrojection by the sixth-century compilers: every early pope shorter than Anicetus is martyred in the LP’s frame, whether or not any historical evidence supports it. Hippolyte Delehaye, the Bollandist who shaped twentieth-century critical hagiography, sharpened the point: in the second century the term martyr in Roman use shaded from “witness who died” to the conventional honorific for any early Roman bishop, and by the time the Liber Pontificalis was compiled the conventional sense had largely overtaken the historical.

The institutional consequence is worth naming carefully, because it is easy to overstate. Unlike Alexander I, whose 3 May feast did appear in the pre-1960 General Roman Calendar and was downgraded in 1960 under John XXIII’s motu proprio Rubricarum instructum, Sixtus I was never in the General Calendar in the first place. There was no martyr title at the universal-calendar level for the 1960 reform to revise. His commemoration lives only in the Roman Martyrology, the more capacious book that records minor saints and local martyrs without setting them as obligatory observances on the universal Mass schedule. The Tridentine Martyrologium Romanum commemorated him on 6 April under the title of pope and martyr; the 2004 editio typica altera of the Martyrology under John Paul II retains the commemoration, though the post-1969 calendar reform shifted some early-papal entries off Easter-overlapping dates and the practical observance of Sixtus’s feast is largely confined to the Diocese of Alatri, where his relics are claimed.

The shape of the Church’s actual judgment, then, is not a 1960 disavowal. It is a quiet century-and-a-half-long withdrawal at the level of critical scholarship—McGiffert in 1890, Duchesne in 1886, Delehaye in 1905—that has never been ratified by a corresponding revision of the Roman Martyrology, because the Martyrology was never designed to make those judgments. It commemorates traditional saints in the tradition’s own terms. That a learned Catholic historian in 2026 does not believe Sixtus was killed for the faith does not require deletion of a sixth-century entry that uses the older convention. It requires only that the historian be honest about what is and is not known.

The Sentences of Sextus and Other Things He Did Not Write

Nothing genuinely written by Sixtus survives. He is, in this, indistinguishable from every other pre-Constantinian Roman bishop except Clement, whose first epistle to the Corinthians is one of the great prizes of early patristic literature. But Sixtus did acquire a literary shadow.

Late in the fourth century, Rufinus of Aquileia translated into Latin a collection of gnomic moral maxims under the title Anulus or Annulus, and in his preface he attributed the original to a Sixtus Romanus, episcopus et martyr. The collection—the Sentences of Sextus—had circulated widely in the early Christian world; Origen had quoted from it; Christian readers found in its terse Pythagorean ethics a usable handbook of moral teaching. Rufinus’s identification gave the popular collection a Roman papal pedigree. Jerome, who had no patience for what he regarded as Rufinus’s sloppy reattributions, dismissed the identification: the author, he said, was a Pythagorean named Sextus, not a pope. Modern scholarship has agreed with Jerome. Henry Chadwick’s 1959 edition restored the work to its actual second-century origin—an originally pagan Pythagorean compilation lightly christianized—and the attribution to either Sixtus I or Sixtus II no longer has a serious defender.⁠¹¹

The pseudonymous tradition did not stop there. In the ninth century the forgers behind the Pseudo-Isidorian Decretals composed letters in Sixtus’s name as part of their larger campaign to lend ancient authority to Carolingian-era episcopal-immunity claims. The standard critical edition of the false decretals is Paul Hinschius’s 1863 Decretales Pseudo-Isidorianae, and modern Pseudo-Isidore scholarship—Horst Fuhrmann’s magisterial three-volume Einfluß und Verbreitung der pseudoisidorischen Fälschungen (1972–73), Eric Knibbs’s 2017 Speculum article on the date of the corpus, Klaus Zechiel-Eckes’s identification of the Carolingian milieu—has only firmed the conclusion that the entire Pseudo-Isidorian collection is a ninth-century fabrication and that the letters in Sixtus’s name within it have no historical value whatever.⁠¹²

The pattern, again, is the one we have seen with every pope so far in the series. A name that originally carried only a position in a list kept acquiring a literary shadow, one era at a time—the Sentences in the fourth century by Rufinus’s pious overreach, the decretals in the ninth by deliberate forgery. The forgers and the well-meaning attributors alike were responding to the same pressure: the early popes, on the surviving evidence, did not write enough.

What We Can Actually Say

Strip the accretions away and a real figure remains. There was a man named Xystus, sixth on Irenaeus’s list and seventh on the Petrine count, who held the Roman see for about ten years in the early second century, whom Irenaeus could still name within a few generations of the event, and whom Eusebius placed in a reasonably coherent line of succession. That much the earliest evidence supports.

What it does not support is the rest. He almost certainly did not institute the Sanctus, which is older than any one bishop’s “institution” of it. He almost certainly did not legislate the touching of sacred vessels or the bearing of apostolic letters by returning bishops, which reflect later Roman ecclesial discipline retrojected by sixth-century compilers. He probably did not die a martyr, on the silence of the only sources from within two centuries of his life. He did not write the Sentences of Sextus, which Jerome already rejected, and he did not write the decretals fabricated in his name by the Pseudo-Isidorian forgers seven centuries after his death.

Apostolic succession requires the names remembered and the line real; it has never required every saint to come with a complete file. Reading Sixtus honestly—keeping the name, the position in the line, and the approximate ten years of his reign, while releasing the Sanctus attribution, the legend of martyrdom, the Sentences, and the Pseudo-Isidorian decretals—is what a tradition does when it actually believes its own claims and has no need to prop them up with borrowed biography. The seventh pope, like the sixth and the fifth, is best honored by being seen for what he was: a name in a list, a link in a chain, a bishop whose contribution to the Church was that he held the see and passed it on.

Next in the series: Pope Saint Telesphorus (coming soon).

Further Reading

• J. N. D. Kelly and Michael J. Walsh, The Oxford Dictionary of Popes, 2nd ed. (Oxford University Press, 2010)—the most reliable quick reference for the early popes
• Eamon Duffy, Saints and Sinners: A History of the Popes, 4th ed. (Yale University Press, 2014)—the most readable honest survey
• Raymond Davis, trans., The Book of Pontiffs (Liber Pontificalis), 3rd rev. ed. (Liverpool University Press, 2010), ISBN 978-1-84631-476-6—the standard English translation, with an essential introduction on the early entries’ reliability
• Henry Chadwick, The Sentences of Sextus: A Contribution to the History of Early Christian Ethics (Cambridge University Press, 1959)—the critical edition that settled the authorship question against any Pope Sixtus
• Horst Fuhrmann, Einfluß und Verbreitung der pseudoisidorischen Fälschungen, 3 vols., MGH Schriften 24/I–III (Stuttgart: Hiersemann, 1972–73)—the magisterial study of the Pseudo-Isidorian Decretals

This post is part of an ongoing series on the popes. You can read about Saint Peter, the first pope, Saint Linus, the second pope, Saint Anacletus, the third pope, Saint Clement, the fourth pope, Saint Evaristus, the fifth pope, and Saint Alexander I, the sixth pope.

Frequently Asked Questions

Who was Pope Saint Sixtus I?

Sixtus I was the seventh Bishop of Rome counting Peter as first, conventionally dated c. 115–125. The earliest source, Irenaeus of Lyons (c. AD 180), gives only his name and his position as “sixth from the apostles” in the Roman succession list, counted from Linus rather than Peter. Eusebius adds that he reigned about ten years. The fuller biography in the sixth-century Liber Pontificalis—institution of the Sanctus, rules about sacred vessels and apostolic letters, a martyr’s death—is regarded by modern scholarship as later accretion rather than fact.

When did Sixtus I reign as pope?

Roughly c. 115 to c. 125. The Liberian Catalogue gives 117 to 126 by consular formula; Eusebius’s Historia Ecclesiastica and Chronicon give slightly different figures that are internally inconsistent; Richard Adelbert Lipsius, comparing the sources in 1869, argued Sixtus must have died by c. 125 after a tenure of about ten years. The modern Annuario Pontificio settles near 115–125.

Did Sixtus I institute the Sanctus in the Mass?

Almost certainly not, in the sense that the Liber Pontificalis claim implies. The Sanctus—the triple acclamation drawn from Isaiah 6:3—is deeply embedded in every early Christian Eucharistic anaphora with surviving textual witnesses and is older than any one bishop’s “institution” of it. The Liber Pontificalis attribution sits four centuries after Sixtus and reflects a sixth-century compiler’s habit of retrojecting primitive liturgical practices to early papal names.

Was Sixtus I a martyr?

Probably not. His martyrdom is recorded in the Liber Pontificalis and repeated in the Western martyrologies, but Irenaeus, who has space to note the martyrdom of Telesphorus immediately after Sixtus, says nothing about Sixtus dying for the faith. Adolf McGiffert summarized the critical verdict for the Nicene and Post-Nicene Fathers: “the fact of his martyrdom rests upon a very late and worthless tradition.” Unlike his predecessor Alexander I, Sixtus was never in the pre-1960 General Roman Calendar, so the 1960 reform had no martyr title to revise; his commemoration as Papa et Martyr lives only in the Roman Martyrology.

When is Sixtus I’s feast day?

6 April in the traditional Roman Martyrology, commemorated as pope and martyr. He is not in the General Roman Calendar in either the Tridentine, 1960, or post-1969 forms; his commemoration is observed mainly in the Diocese of Alatri, which claims his relics from a 1132 translation (a competing tradition places the relics in a Romanesque crypt at Alife in Campania).

Did Sixtus I write anything that survives?

No. The Sentences of Sextus—a popular early Christian gnomic collection—was attributed to him in the late fourth century by Rufinus of Aquileia, but Jerome rejected the identification, and modern scholarship (notably Henry Chadwick’s 1959 critical edition) has confirmed that the author was a Pythagorean named Sextus, not any Pope Sixtus. The ninth-century Pseudo-Isidorian Decretals forge letters in his name, but these are not genuine.

Is the Xystus in the Roman Canon Sixtus I?

No. The Xystus commemorated in the Roman Canon of the Mass is Xystus II, the third-century pope who was killed by Roman officials on 6 August 258 while celebrating the liturgy in the cemetery of Praetextatus. The traditional Roman commemoration of Xystus II falls on the same day, alongside the Transfiguration.

Notes

1. 1. Irenaeus of Lyons, Against Heresies III.3.3 (c. AD 180), translated in Ante-Nicene Fathers, vol. 1, eds. Alexander Roberts and James Donaldson, rev. A. Cleveland Coxe (Buffalo: Christian Literature Publishing Co., 1885). Available at NewAdvent.org.

2. 2. Eusebius, Historia Ecclesiastica IV.5, translated by A. C. McGiffert in Nicene and Post-Nicene Fathers, 2nd series, vol. 1 (Buffalo: Christian Literature Publishing Co., 1890). Available at CCEL.org. McGiffert numbers the bishops from Peter and Paul without counting Peter himself; on that reckoning Sixtus is “sixth from the apostles” (Irenaeus) and Telesphorus is “seventh in succession from the apostles” (Eusebius). The modern Catholic count taking Peter as the first pope makes Sixtus the seventh.

3. 3. Eusebius, Historia Ecclesiastica IV.4, in McGiffert’s NPNF translation; available at CCEL.org.

4. 4. McGiffert, NPNF apparatus to Eusebius HE IV.4, n. 991, citing Richard Adelbert Lipsius, Chronologie der römischen Bischöfe bis zur Mitte des vierten Jahrhunderts (Kiel: Schwers, 1869), 183–192. Available at CCEL.org.

5. 5. Liberian Catalogue, preserved in the Chronograph of 354; quoted Latin a consulatu Nigri et Aproniani usque Vero III et Ambibulo = the consulships of M. Annius Verus III and M. Vibius Ambibulus (AD 126) marking the terminus. Cited in Michael Ott, “Pope St. Sixtus I,” The Catholic Encyclopedia, vol. 14 (New York: Robert Appleton Company, 1912), citing Louis Duchesne, ed., Le Liber Pontificalis, vol. 1 (Paris: Ernest Thorin, 1886), 128. Available at NewAdvent.org.

6. 6. Ott, “Pope St. Sixtus I”: “All authorities agree that he reigned about ten years.”

7. 7. Ott, “Pope St. Sixtus I”: “in the oldest documents, Xystus is the spelling used for the first three popes of that name.” On the Greek etymology (ξυστός, “polished”) and the probable Latin pun with sextus, “sixth,” see also the discussion in standard reference works, e.g. George L. Williams, Papal Genealogy: The Families and Descendants of the Popes (Jefferson, NC: McFarland, 2004), 9, ISBN 978-0-7864-2071-1, which notes that Sixtus I was the sixth pope after Peter on the Petrine count and asks whether the name “Sixtus” is derived from sextus.

8. 8. Ott, “Pope St. Sixtus I,” summarizing the three ordinances from the Liber Pontificalis (ed. Duchesne, I.128). On the anachronism of the Sanctus attribution, see Josef A. Jungmann, The Mass of the Roman Rite: Its Origins and Development (Missarum Sollemnia), trans. Francis A. Brunner, 2 vols. (New York: Benziger, 1951–55), vol. 2, on the Preface and the Sanctus; the Western textual witnesses for the Sanctus in the Eucharistic anaphora are routinely dated from the mid-fourth century onward and reflect a much older liturgical practice.

9. 9. Ott, “Pope St. Sixtus I”: “The ‘Felician Catalogue’ of popes and the various martyrologies give him the title of martyr. His feast is celebrated on 6 April. He was buried in the Vatican, beside the tomb of St. Peter.” On the burial tradition and the disputed later translation of relics, see Ott’s discussion of the 1132 Alatri translation, citing O. Jozzi, Il corpo di S. Sisto I., papa e martire rivendicato alla basilica Vaticana (Rome, 1900), against the Alatri tradition. A competing tradition places the relics in a Romanesque crypt at Alife (Campania), brought there by Rainulf III in the twelfth century; see the summary at Wikipedia, “Pope Sixtus I”. The relic-location claims are not uniform and likely cannot be reconciled from the surviving evidence.

10. 10. McGiffert, NPNF apparatus to Eusebius HE IV.4, n. 991: “Like most of the other early Roman bishops he is celebrated as a martyr in the martyrologies, but the fact of his martyrdom rests upon a very late and worthless tradition.” On the Tridentine and current Roman Martyrology entries (6 April for the older RM, retained in the 2004 editio typica altera), see the discussion in Ott, “Pope St. Sixtus I.” On the 1960 General Roman Calendar reform under John XXIII’s Rubricarum instructum, see the published list of suppressions and downgrades; Sixtus I was never in the General Calendar in any form, so no GC entry was revised.

11. 11. Henry Chadwick, The Sentences of Sextus: A Contribution to the History of Early Christian Ethics, Texts and Studies, n.s. 5 (Cambridge: Cambridge University Press, 1959), establishes the critical text and the modern scholarly consensus that the work is an originally pagan Pythagorean compilation lightly christianized in the late second century, not a composition of any Pope Sixtus. Jerome’s objection appears in his prefatory remarks on Rufinus’s translation; Rufinus’s own preface attributing the work to Sixtus Romanus, episcopus et martyr is preserved in the Latin tradition and translated in the Nicene and Post-Nicene Fathers, 2nd series, vol. 3.

12. 12. Paul Hinschius, ed., Decretales Pseudo-Isidorianae et Capitula Angilramni (Leipzig: Tauchnitz, 1863), remains the only complete critical edition of the Pseudo-Isidorian corpus; the forgeries in Sixtus’s name appear within. The forgery was first conclusively demonstrated by David Blondel, Pseudoisidorus et Turrianus vapulantes (Geneva, 1628). For modern Pseudo-Isidore scholarship, see Horst Fuhrmann, Einfluß und Verbreitung der pseudoisidorischen Fälschungen, 3 vols., MGH Schriften 24/I–III (Stuttgart: Hiersemann, 1972–73); Klaus Zechiel-Eckes, Fälschung als Mittel politischer Auseinandersetzung: Ludwig der Fromme (814–840) und die Genese der pseudoisidorischen Dekretalen (Paderborn: Schöningh, 2011); and Eric Knibbs, “Ebo of Reims, Pseudo-Isidore and the Date of the False Decretals,” Speculum 92, no. 1 (2017): 144–183. The standard summary remains the 1908 Catholic Encyclopedia entry on the False Decretals, available at NewAdvent.org.