1 John 5:7 (AV)
For there are three that bear record in heaven,
the Father, the Word, and the Holy Ghost:
and these three are one.
A number of fine scholars, generally Trinitarian, have theorized that the verse dropped out of the Greek manuscript line largely because the Orthodox (who were faced with a split manuscript line) preferred the text without “and these three are one”. In this textual theory the phrase was seen as too “Sabellian”, a denial of distinct persons in the Godhead.
The original split line may have been caused by homoeoteleuton, eye skip, die to the similarity of the heavenly and earthly witnesses verse.
Pure Bible Forum
scholars theorizing that the Sabellian controversies contributed to the Greek ms line drop
https://www.purebibleforum.com/index...line-drop.671/