Please note the followings:
Tertullian, Adversus Praxean of RB 215
Against Praxeas ( Heresies) 215AD
And so the connection of the Father, and the Son, and of the Paraclete makes three cohering entities, one cohering from the other, which three are one entity" refers to the unity of their substance, not to the oneness of their number.
Priscillian, Liber Apologeticus 380 AD
As John says "and there are three which give testimony on earth, the water, the flesh the blood, and these three are in one, and there are three which give testimony in heaven, the Father, the Word, and the Spirit, and these three are one in Christ Jesus."
These scholars supported or proved the Comma was the part of the genuine Bible:
Cyprian - 250 AD, Athanasius 350 A.D., Priscillian -385 AD, Jerome 420 AD, Fulgentius (late 5th century), Cassiodorus, Isidore of Seville, Jaqub of Edessa, Thomas Aquinas, John Wycliffe, Desiderus Erasmus, Stephanus, Lopez de Zuniga, John Calvin, Theodore Beza, Cipriano de Valera, John Owen, Francis Turretin, John Wesley, John Gill, Matthew Henry.
John Gill said:
JOHN GILL commenting on 1 John 5:7 - "As to the old Latin interpreter, it is certain it is to be seen in many Latin manuscripts of an early date, and stands in the Vulgate Latin edition of the London Polyglot Bible: and the Latin translation, which bears the name of Jerome, has it, and who, in an epistle of his to Eustochium, prefixed to his translation of these canonical epistles, complains of the omission of it by unfaithful interpreters."
1 John 5:7 - Meaning and Commentary on Bible Verse
Among the 9200 Latin manuscripts dated before 1500AD the majority have the Comma.
Father, Word, Spirit instead of Father, Son, Spirit is a typical Johannine style.
As I said before, without the Comma, the sentences don't make sense due to the gender discrepancy.
Oi Treis should have been : Ta Treis because the previours words are all neutral gender.
In other words, the current WH-NA is wrong in grammar
The gnosism in the Western Roman Empirre region and the Sabelianism in the Eastern Roman Empire region caused
the elimination of the Comma.
Erasmus knew that the Comma was the part of the genuine Bible, but couldn't insert it without the supporting Greek manuscripts and promised that he would include it as soon as anyone could provide any manuscripts. Then someone brought the manuscripts supporting it. So, it was included. He didn't manufacture the manuscripts. He couldn't have all the manuscripts necessary for the right compilation, which is quite understandable.
Even if the heretics deleted the Comma dilligently from the manuscripts, many scholars quoted the Comma in their books.
God knows the full history and I believe the Comma is the genuine part of the Bible.
Eliyahu