Good book debunking the Majority Text position with many proofs (not same as the Byzantine manuscripts that underline Textus Receptus/TR editions that underlie the amazing KJB): https://faithsaves.net/wp-content/uploads/2016/02/KJV-Majority-Text-Moorman.pdf 
("When KJV Departs from the Majority Text") The book shows how Textus Receptus/TR is right against Majority Text & how the "Majority Text fails in many places including Revelation & 1 John 5:7-8, as seen in Chapter 5. Also, Majority Text is partially based on Von Soden's New Testament which takes out most of 1 John 5:7 (Anti Modern Versions checked that as well)

Majority Text position denies 1 John 5:7 and other verses (attacked by hereticks and Arians in the 300s-400sAD) for not being in a majority of manuscrupts, BUT you do not need to have a majority of manuscripts but just even one manuscript that God can use to preserve his words. The fatal flaw of both the Majority Text position & any printed Majority Text is they deny preservation of all Scripture