Some comments found at www.bible-researcher.com › Textual Criticism:
“We give below the comments of Dr. Bruce M. Metzger on 1 John 5:7-8, from his book, A Textual Commentary on the Greek New Testament, 2nd ed. (Stuttgart, 1993)......
(A) External Evidence.
(1) The passage is absent from every known Greek manuscript except eight, and these contain the passage in what appears to be a translation from a late recension of the Latin Vulgate. Four of the eight manuscripts contain the passage as a variant reading written in the margin as a later addition to the manuscript. The eight manuscripts are as follows:
61: codex Montfortianus, dating from the early sixteenth century.
88: a variant reading in a sixteenth century hand, added to the fourteenth-century codex Regius of Naples.
221: a variant reading added to a tenth-century manuscript in the Bodleian Library at Oxford.
429: a variant reading added to a sixteenth-century manuscript at Wolfenbüttel.
629: a fourteenth or fifteenth century manuscript in the Vatican.
636: a variant reading added to a sixteenth-century manuscript at Naples.
918: a sixteenth-century manuscript at the Escorial, Spain.
2318: an eighteenth-century manuscript, influenced by the Clementine Vulgate, at Bucharest, Rumania.
(2) The passage is quoted by none of the Greek Fathers, who, had they known it, would most certainly have employed it in the Trinitarian controversies (Sabellian and Arian). Its first appearance in Greek is in a Greek version of the (Latin) Acts of the Lateran Council in 1215.
(3) The passage is absent from the manuscripts of all ancient versions (Syriac, Coptic, Armenian, Ethiopic, Arabic, Slavonic), except the Latin; and it is not found (a) in the Old Latin in its early form (Tertullian Cyprian Augustine), or in the Vulgate (b) as issued by Jerome (codex Fuldensis [copied a.d. 541-46] and codex Amiatinus [copied before a.d. 716]) or (c) as revised by Alcuin (first hand of codex Vallicellianus [ninth century]).
The earliest instance of the passage being quoted as a part of the actual text of the Epistle is in a fourth century Latin treatise entitled Liber Apologeticus (chap. 4), attributed either to the Spanish heretic Priscillian (died about 385) or to his follower Bishop Instantius. Apparently the gloss arose when the original passage was understood to symbolize the Trinity (through the mention of three witnesses: the Spirit, the water, and the blood), an interpretation that may have been written first as a marginal note that afterwards found its way into the text. In the fifth century the gloss was quoted by Latin Fathers in North Africa and Italy as part of the text of the Epistle, and from the sixth century onwards it is found more and more frequently in manuscripts of the Old Latin and of the Vulgate. In these various witnesses the wording of the passage differs in several particulars. (For examples of other intrusions into the Latin text of 1 John, see 2.17; 4.3; 5.6, and 20.)”
The Comma is no part of the Bible. It is spurious.
Do any of the oldest texts have any punctuation at all?
You are missing the point.
The fact that the comma appears in the Vulgate says that the trinitarian discussion was already in full bloom. That Tertullian used the word trinity says it was a discussion then. The trinitarian discussion is the topic here, and showing that it goes back to the beginning of the church.
Which simply makes all other biblical texts clearly to be taken in a trinitarian light.