Early Biblical, Historical Evidence shows 1 John 5:7-8’s historical existence & the doctrine, existence, & verifiability of the Godhead/the Trinity are spoken during & well known as far back as less than 30 years after John wrote Revelation in A.D. 95

Early 100ADs-Polycarp said: "O Lord God almighty...I bless you and glorify you through the eternal and heavenly high priest Jesus Christ, your beloved Son, through whom be glory to you, with Him and the Holy Spirit,” (n. 14, ed. Funk; PG 5.1040)."

AD 150-Tatian refers to 1 John 5:7 when talking on Mark 16:
 "Go now into all the world, and preach my gospel in all the creation; and teach all the peoples, and baptize them in the name of the Father and the Son and the Holy Spirit" (Section LV, Tatian's Diatessaron)

AD 157 -Vaudois'/Waldensians' Latin Bible quotes 1 John 5:7-8:
"Quoniam tres sunt, gui testimonium dant in coelo: Pater, Verbum, et Spiritus sanctus: et hi tres unum sunt. Et tres sunt, qui testimonium dant in terra: Spiritus, et aqua, et
sanguis: et hi tres unum sunt."
The above Latin Bible words in 1 John 5:7, matches 1611 King James Bible's English words in 1 John 5:7:
For there are three that beare record in heauen, the Father, the Word, and the holy Ghost:
and these three are one.

AD 200 -In Against Praxeas, Tertullian wrote, “which distributes the Unity into a Trinity, placing in their order [20] the three Persons-the Father, the Son, and the Holy Ghost: three, however, not in condition, [21] but in degree; [22] not in substance, but in form; not in power, but in aspect; [23] yet of one substance, and of one condition, and of one power, inasmuch as He is one God, from whom these degrees and forms and aspects are reckoned, under the name of the Father, and of the Son, and of the Holy Ghost. [24]"
(Tertullian, Against Praxeas, Chapter II)

A.D. 250 -In Treatises 1 5:423, Cyprian wrote,"The Lord says 'I and the Father are one' and likewise it is written of the Father and the Son and the Holy Spirit, 'And these three are one.'[The Ante-Nicene Fathers: Translations of the Writings of the Church Fathers Down to A.D.325 (New York: Charles Scribner's Sons, 1926), 5:423.]

AD 300s: In Disputatio Contra Arium, Athanasius quoted 1 John 5:7's words "these three are one"
In Greek: "Πρὸς δὲ τούτοις πᾶσιν Ἰωάννης φάσκει·  «Καὶ οἱ τρεῖς τὸ ἕν εἰσιν."
English Translation: "In addition to all these, John affirms, ‘and these three are one.‘"(Translation by KJV Today)
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385 AD -Priscillian cites 1 John 5:7 in his book,Liber Apologeticus
"As John says '...and there are three which give testimony in heaven, the Father, the Word, and the Spirit, and these three are one...' "

A.D. 485 -Against Arianism [which denies Jesus is God] heresy, Eugenius, spokesman for 400 Christian pastors, said at the Council of Carthage, ”and in order that we may teach until now, more clearly than light, that the Holy Spirit is now one divinity with the Father and the Son.It is proved by the evangelist John, for he says, 'there are three which bear testimony in heaven, the Father, the Word, and the Holy Spirit, and these three are one.’ ” [Victor of Vitensis, Historia persecutionis Africanae Prov, 2.82 [3.11]; CSEL 7, 60. Translated by Michael Maynard in A History of the Debate Over 1 John 5:7-8 (Tempe, AZ: Comma Publications, 1995),43.]

Sixth century (AD 500s)-Codex Fuldenis refers to 1 John 5:7's words "these three are one" when quoting 1 John 5:7 and 1 John 5:8
"Quia tres sunt qui testimonium dant: Spiritus et aqua et sanguis et tres unum sunt.”

AD 700 -Jaqub of Edessa (wrote in Syriac), a well-known church writer from the seventh century, inscribed, "The soul and the body and the mind which are sanctified through three holy things; through water and blood and Spirit, and through the Father and the Son and the Spirit."

Modern versions are wrong by omitting 1 John 5:7 & making unbiblical, anti-historical, heretickal attack on the Godhead/Trinity.
KJB is 100% truthful by preserving 1 John 5:7-8
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@AntiModernVersions