This is what someone from a local bookstore is claiming based on a book that comes to this conclusion.
The Disciple Whom Jesus Loved - who was that beloved disciple?
The whole book is on line
Who was the disciple that Jesus loved? Trust the Bible evidence.
Conclusion
This Bible study presented evidence in two cases. In the first it was shown that the Apostle John wasn’t “the disciple whom Jesus loved” (the author of the fourth Gospel). In the second facts were cited that indicate this unnamed beloved disciple was Lazarus. Now, let’s review the evidence that's been presented so far. Pause to pray and ask God to use His Word to lead you to the truth. (This is always a bad sign)

He would have had to write 1,2,3 John as well because of the similarity of all these writings.

Bible study on the beloved disciple, who was the disciple Jesus loved?

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Erick Bohndorf PCA, KS
http://qayaqtraveler.blogspot.com/
Jeremiah 23:16,17, "Thus says the Lord of hosts: “Do not listen to the words of the prophets who prophesy to you, filling you with vain hopes. They speak visions of their own minds, not from the mouth of the Lord. 17They say continually to those who despise the word of the Lord, ‘It shall be well with you’; and to everyone who stubbornly follows his own heart, they say, ‘No disaster shall come upon you."