You are saying John was not exhaustive because what’s in the book of John is all we need? What do we do with the other 26 books?
I’m saying that John was not exhaustive for the purposes for which HE was writing at the time. That doesn’t mean the other apostle’s writings aren’t needed. Just as Paul wrote the Colossians for the purposes he needed to write the Colossians or the Ephesians or the Corinthians.
For the purposes at the time for which he was writing his gospel account, and more than likely it was to dispel the gnostic heresies going around at the time, John felt he didn’t need to be exhaustive in his gospel account.
Scripture is indeed intended to get us to believe in Christ, but nowhere does it tell us that Scripture is the source to the exclusion of Tradition or of the Church. It actually says the opposite. Nor does it say Scripture is the totality of Revelation.
Faith comes by hearing and hearing by the Word of God. The Word of God is Scripture. The Holy Spirit giving illumination to understand and believe. Nowhere does the Scripture say that tradition is necessary. The Scripture is the living and active:
Heb 4:12 For the word of God is living and effectual, and sharper than any two-edged sword, piercing even to the division of soul and spirit, and of joints and marrow, and is a discerner of the thoughts and intentions of the heart.
Jesus himself said in response to the devil’s temptations:
Mat 4:4 But He answered and said, "It is written, ‘Man shall not live by bread alone,
but by every word that proceeds out of the mouth of God.’ "
That’s God’s word…for every temptation the devil gave Jesus, Jesus answered with “It is written…” meaning the word of God, not tradition. If Jesus depended upon Scripture to refute and rebuke Satan, what else do I need?
2Ti 3:14 But you must continue in the things which you have learned and been assured of, knowing from whom you learned them,
2Ti 3:15 and that from childhood **you have known the Holy Scriptures, which are able to make you wise to salvation through faith which is in Christ Jesus. **
2Ti 3:16 All Scripture is given by inspiration of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness,
2Ti 3:17 that the man of God may be proficient, having been thoroughly equipped for every good work.
Now, if Paul told Timothy that the Holy Scriptures could make him wise, if Scripture can thoroughly equip me in doctrine, reproof and correction and instruction in righteousness so that I can be thoroughly and completely equipped and not lacking anything for my Christian walk (I’m expanding on the true meaning of the Greek) then why do I need tradition?!
Also, if Paul, an apostle called and instructed by Christ Jesus himself, was not threatened or undermined by the Bereans checking the Scriptures to see if what Paul said was true (Acts 17:11) but rather Paul called them noble…then why shouldn’t we?
Notice Paul didn’t call them noble for checking with traditions but rather with the Scriptures. That’s the acid test that counts.