And yet when Rome formalized its canon at the Council of Trent in the 1500s not one of the myriad of writings Roman Catholics selectively cite as "tradition" were included.
That is very telling.
If one just had the Bible, and if one just had the book of John from the Bible, one would have all they need to know how to have salvation.
That cannot be said about "tradition".
Also, if it's true that if I had just the Gospel of John, I would have what I need for salvation (that may be trrue in a sense!) I could just as truly say that If I had just the first CHAPTER of John I would have what I need, since in tells me about Christ, the Light which "enlightens every man", who was come into the world, and "from His fullness we have all received."
Or perhaps I would need only a couple of verses from Matthew:
Jesus replied: "Love the Lord your God with all your heart and with all your soul and with all your mind.’ This is the first and greatest commandment. And the second is like it: ‘Love your neighbor as yourself.’In which case, all we need is maybe Deuteronomy 6:5 or Deuteronomy 10:12.All the Law and the Prophets hang on these two commandments."
But this is minimalism, or a most unwise reductionism. If that's "it", then--- hey! The Bible comprises 30,000+ verses! And so, most of what God has given us, is a pile of unneeded redundancies --- a pile of distractions, as it were.
That's major error. God forbid that anyone should think that.
Philip: "Thinkest thou that thou understandest what thou readest?"
The Ethiopian royal official: : "And how can I, unless some man show me?" (Acts 8:26-40)