We saw from Jerome that the heavenly witnesses was a verse that was creating disputes and discords, in his Psalm 91 homily and in the Vulgate Prologue. There are a number of indications that the verse was central focus, and often surpressed, from the Regensburg manuscript, to the Discipina Arcana, to a special focus on 1 John. And in the Disputation of Arius and Athanasius the verse is referenced.

Even in the time of Constantine, there is a reference to a "single passage of scripture" creating discord between what we today call the Orthodox and the Arians. (Barnes or Stevenson points out that we should not see this anachronistically, by putting the current accepted ideas into Constantine pre-Nicaea.)

Constantine and Eusebius (1981)
Timothy David Barnes
https://books.google.com/books?id=LGDjJK-JeSwC&pg=PA213

"Constantine .. then returned to Nicomedia, where his presence is attested on 25 February 3 323.25 He himself explains the change of plan: he did not wish to see and hear the theological bickering which divided the East.26 The Arian controversy forced itself on his attention just at the period when he most wished to concentrate on converting pagans to Christianity. By 324 not only were bishops denouncing one another, but congregations were divided into two parties, and in the theater pagans taunted Christians about their dissensions.27

Constantine felt a moral duty to intervene in the dispute. He wrote a letter to Alexander and Arius urging them to settle their differences peaceably and entrusted it to Ossius of Corduba, who had probably remained constantly at court since 312.28 In fact, no real possibility of compromise existed. If Constantine hoped to mediate the quarrel, it was because he set a lower value on theological definitions, which he considered pedantic, than on making the Roman Empire Christian.29

The letter which Ossius took to Alexandria repeatedly rebukes Alexander and Arius for quarreling over questions which are of no importance. The bishop ought not to have interrogated his priests about their exegesis of a single passage of Scripture, and Arius ought to have maintained silence; both question and answers were produced by the contentious spirit of idle leisure. Their dispute is far less serious than the Donatist schism which divides Africa.30 For the central doctrines of the divine law are not in dispute, nor has anyone introduced a novel way of worshiping God. Since the debate is a philosophical one, Constantine urges Alexander and Arius to behave like philosophers; their agreement on the main issues far outweighs minor differences, especially because they disagree on a question where the feebleness of the human intellect hinders the clear exposition or apprehension of the truth.31
Documents of the Early Arian Controversy – Emperor Constantine to Alexander of Alexandria and Arius
http://www.fourthcentury.com/urkunde-17/

6.) I understand that the origin of the present controversy is this. When you, Alexander, demanded of the priests what opinion they each maintained respecting a certain passage in Scripture, or rather, I should say, that you asked them something connected with an unprofitable question. You then, Arius, inconsiderately insisted on what ought never to have been speculated about at all, or if pondered, should have been buried in profound silence.