CRITICAL INTERNAL EVIDENCE SUPPORTS THE "COMMA"
If I John 5:6-8 is removed from the Greek text, the two resulting loose ends will not join together grammatically. The Greek language has "gender" in its noun endings (as do many other languages). Neuter nouns normally require neuter articles (the word "the" as in "the blood" is the article). But the article in verse 8 of the shortened reading as found in the Greek that is the foundation of the new versions (verse 7 of the King James Greek text) is masculine. Thus the new translations read "the Spirit (neuter), the water (neuter), and the blood (neuter): and these three (masculine!! - from the Greek article "hoi") are in one." Consequently three neuter subjects are being treated as masculine (see below where the omitted portion is italicized). If the "Comma" is rejected it is impossible to adequately explain this irregularity. In addition, without the "Comma" verse 7 has a masculine antecedent; three neuter subjects (nouns in vs.8) do not take a masculine antecedent. Viewing the complete passage it becomes apparent how this rule of grammer is violated when the words are omitted.
5:6 ... And it is the Spirit (neuter) that beareth witness (neuter), because the Spirit (neuter) is truth.
5:7 For there are three (masculine) that bear record (masculine) in heaven, the Father (masculine), the Word (masculine), and the Holy Ghost (neuter): and these three (masculine) are one (masculine).
5:8 And there are three (masculine) that bear witness (masculine) in earth, the Spirit (neuter), and the water (neuter), and the blood (neuter): and these three (masculine) agree in one.
When we inquire of the scholars an accounting for this strange situation, the reply is that the only way to account for the masculine use of the three neuters in verse 8 is that here they have been "personalized". Yet we observe that the Holy Spirit is referred to twice in verse 6 and as He is the third person of the Trinity this would amount to "personalizing" the word "Spirit" but the neuter gender is used. Therefore as Hills noted since personalization did not bring about a change of gender in verse 6, it cannot fairly be pleaded as the reason for such a change in verse 8.