For there are three that bear record in heaven, the Father, the Word, and the Holy Ghost: and these three are one.

1 John 5:7

To be honest, I have no idea why this verse is called the Johannine Comma. In my opinion, the evidence is overwhelming in support of it. I can only list for your consideration a couple of the articles I have read concerning it. Personally, I do not see a reason for the fight. It changes nothing whether it is there or not. No doctrine is changed either way. The Trinity is biblical, with or without it; it does support and makes a clear statement concerning it.

I can only recommed that time is alotted to examine the debate.

• https://av1611.com/kjbp/faq/holland_1jo5_7.html
• https://www.bereanpatriot.com/the-johannine-comma-of-1-john-57-8-added-or-removed/

Far from challenging the textual reliability of Scripture, the Johannine Comma’s debate has shown how careful historical scrutiny (analysis of Greek manuscripts, translations, and patristic quotations) ultimately reinforces confidence in the text. When a later scribal addition is identified, it does not discredit the entire Bible but instead showcases the earnestness of scholarly and ecclesiastical communities in preserving and recovering what the original authors wrote.

https://biblehub.com/q/does_the_’johannine_comma’_affect_bible_consistency.htm