Ockham's razor supports the simple explanation, John wrote the verse in his Gospel.
A plain misapplication of Ockham's razor. Here is the Comma according to scholar Raymond E. Browne (The Epistles of John 1982), which largely agrees with my own opinions to date.
Bibliography: p. 786-787
archive.org
First he says this of the evidence as to the Comma's inauthenticity:
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If we turn from the Greek to ancient versions other than the Latin, we note that the Comma is absent from all pre-1500 copies of the Syriac. Coptic, Armenian, Ethiopic. Arabic, and Slavonic translations of the NT—an incredible situation if it were once part of the original Greek text of I John. The Oriental church writers do not seem to know the Comma before the thirteenth century.
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As to who created the Comma, he seems to agree it was likely Priscillian the modalist or one of his followers and not the Carthaginian writers Tertullian, Cyprian, Augustine (of this, more later, perhaps)
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C.
The Origins of the Comma
Granted that the Comma was not written by the author of I John, when, where, and how did it originate? The first clear appearance of the Comma is in the
Liber apologeticus 1.4 (CSEl. 18, 6) of Priscillian who died in 385. Priscillian seems to have been a Sabellian or modalist for whom the three figures in the Trinity were not distinct persons but only modes of the one divine person. Seemingly he read the Comma ("Father. Word, and Holy Spirit: and these three are one [in Christ Jesus]") in that sense: and because the Comma fits Priscillian's theology many have surmised that he created it. Before commenting on that, let me survey the subsequent history of the Comma among Latin writers before its appearance two hundred or three hundred years later in the extant MSS. of the NT, as discussed above.
1. The Comma in Writers after Priscillian (A.D. 400-650)
Whether or not modalist in origin, the Comma could be read in an orthodox trinitarian manner. For instance, it was invoked at Carthage in 484 when the Catholic (anti-Arian) bishops of North Africa confessed their faith before Huneric the Vandal (Victor of Vita,
Historia pcrsecutionis Africanae Prov. 2.82 [3.11]; CSEL 7, 60). Indeed, in the century following Priscillian, the chief appearance of the Comma is in tractates defending the Trinity. In PL 62, 237-334 there is a work
De Trinitate consisting of twelve books. Formerly it was attributed to the North African bishop Vigilius of Thapsus who was present at the Carthage meeting; it has also been designated Pseudo-Athanasius; but other guesses credit it to a Spanish scholar such as Gregory of Elvira (d. 392) or Syagrius of Galicia (co. 450).22 Recently the first seven books have been published (CC 9, 3-99) as the work of Eusebius of Vercelli (d. 371), but not without debate (see CPL #105). In any case, the work is probably of different times, e.g., Books 1-7 written just before 400, and 8-12 at a period within the next 150 years. In Books 1 and 10 (PL 62, 243D. 246B, 297B) the Comma is cited three times. Another work on the Trinity consisting of three books
Contra Varimadum has also been the subject of speculation about authorship and dating,23 but North African origin
ca. 450 seems probable. The Comma is cited in 1.5 (CC 90, 20-21). Victor, the bishop of Vita in North Africa toward the end of the Vandal crisis
(ca. 485), wrote the
Historia persecutions Africanae Provinciae in the course of which he cited the Comma as representing the testimony of John the evangelist (2.82 in CSEL 7, 60; 3.11 in PL 58, 227C). Early in the next century the Comma was known as the work of John the apostle as we hear from Fulgentius, the bishop of Ruspe in North Africa (d. 527), in his
Responsio contra Arianos (Ad 10; CC 91. 93), and in his
De Trinitate (1.4.1; CC 91 A, 636). The Vandal movements in the fifth century brought North Africa and Spain into close relationship, and the evidence listed above shows clearly that the Comma was known in those two regions between 380 and 550. How and when was it known elsewhere?
To the period before 550 belongs a
Prologue to the Catholic Epistles, falsely attributed to Jerome, which is preserved in the Codex Fuldensis (PL 29, 827-31). Although the Codex itself does not contain the Comma, the
Prologue states that the Comma is genuine but has been omitted by unfaithful translators. The
Prologue has been attributed to Vincent of Lcrins (d. 450) and to Peregrinus (Kunstle, Ayuso Marazucla), the fifth-century Spanish editor of the Vg. In any case, Jerome's authority was such that this statement, spuriously attributed to him, helped to win acceptance for the Comma.
In Italy Cassiodorus (d.
ca. 583) cited the Comma in his commentary
In Epistolam S. Joanηis ad Parthos (10.5.1; PL 70, 1373A), although it is not clear that he thought it belonged to the Bible and was written by John. The work of Cassiodorus was a channel through which knowledge of the Comma came also to France. As for England, no MS. of the commentary on the Cath-olic Epistles by Venerable Bede (d. 735) was thought to show knowledge of the Comma, although two inferior MSS. had the phrase "on earth" after "testify" in the standard text of I John 5:7-8. C. Jenkins has now found a late-twelfth-century MS. (177 at Balliol, Oxford) that does contain the Comma, but by that date it may well have been read into Bede from the Latin Bible.
Overall, then, the evidence from the writers of the period 400-650 fits in with the evidence of the Latin Bible where the Comma begins to appear after 600 in the MSS. known to us. (Isidore of Seville, d. 636. who shows knowledge of the Comma in his
Tesiimonia divinae Scripturae 2 |PL 83, 1203C], if the work is genuinely his, may have served as a bridge to the biblical MSS., for his name is connected with editorial work on the Latin Bible.) The Comma was known in North Africa and Spain, and knowledge of it elsewhere was probably derivative from North African and Spanish influence.
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The following picture emerges from the information drawn from the church writers. In North Africa in the third and fourth centuries (a period stretching from Tertullian to Augustine), the threefold witness of the Spirit, the water. and the blood in I John 5:7-8 was the subject of trinitarian reflection, since the OL translation affirmed that "these three
are one." Woven into this reflection were statements in GJohn offering symbolic identifications of each of the three elements, plus John 10:30, "The Father and I are one." Eventually, in the continued debates over the Trinity, the modalist Priscillian or some predecessor took the Johannine equivalents of Spirit, water, and blood, namely, Father, Spirit, and Word, and shaped from them a matching statement about another threefold witness that was also one. If the phrase "on earth" had already appeared in the OL reference to the Spirit, the water, and the blood, the counter-part "in heaven" was obvious for the added threefold witness of the divine figures. At first this added witness was introduced into biblical MSS. as a marginal comment on I John 5:7-8, explaining it; later it was moved into the text itself. Some who knew the Comma may have resisted it as an innovation, but the possibility of invoking the authority of John the Apostle on behalf of trinitarian doctrine won the day in the fifth-century debates against the Arians and their Vandal allies. The close connection of Spain to North Africa explains that the Comma appeared first in Latin biblical texts of Spanish origin. In summary, Greeven ״ phrases it well:
"The Johannine Comma must be evaluated as a dogmatic expansion of the scriptural text stemming from the third century at the earliest in North Africa or Spain."