You belive in Scripture, correct?
Then why don't you believe this?
John 21: (We'll be using the KJV today to keep things on even footing): "And there are also many other things which Jesus did, the which, if they should be written every one, I suppose that even the world itself could not contain the books that should be written. Amen."
The Bible Itself declares that it doesn't contain everything.
Thus we have Holy Tradition -- straight from the Bible.
Typical Roman misuse of Scripture. You cannot take an isolated verse and prove anything.
eg. Matthew 16:18
And I tell you that you are Peter, and on this rock I will build my church, and the gates of Hades will not overcome it.
What’s the next verse say? There’s your answer.
Not to mention the fact that Jesus sent them the Spirit of Truth to guide them and disclose what is to COME.
…John: 16:13”But when He, the Spirit of truth, comes, He will guide you into all the truth; for He will not speak on His own initiative, but whatever He hears, He will speak; and He will disclose to you what is to come. 14”He will glorify Me, for He will take of Mine and will disclose it to you. 15”All things that the Father has are Mine; therefore I said that He takes of Mine and will disclose it to you.…
It is obvious from this passage that there were things that Jesus had not yet taught His Apostles.
You try and quote John to assert a proof for the extra-scriptural requirements for salvation, but skip the verse showing the sufficiency of the Gospel of John containing the things needed for salvation. Which is it? Don't you believe Scripture...correct?