Why, the two quotes from Jonh show that there are things that are of Christ not described in the Scripture, but communicated to the Church. The third quote, from 2 Timothy says that all (all, mind you, including the parts Luther threw out) scripture is inspired and profitable for the education of the clergy.
The Sola Scriptura remains an extrascriptural superstition.
First of all, they are in the scriptures to start with. Secondly the whole bible is one continuous story of the working of the Holy Spirit before and after Jesus. Secondly, all things were made by him, for him, so of course they are greater than the world itself. God gave man a complete bible, enough for him. To seek outside what God has given you (let alone make it up)will have consequences.
Main Entry: su·per·sti·tion
Pronunciation: "sü-p&r-'sti-sh&n
Function: noun
Etymology: Middle English supersticion, from Anglo-French, from Latin superstition-, superstitio, from superstit-, superstes standing over (as witness or survivor), from super- + stare to stand -- more at STAND
1 a : a belief or practice resulting from ignorance, fear of the unknown, trust in magic or chance, or a false conception of causation b : an irrational abject attitude of mind toward the supernatural, nature, or God resulting from superstition
2 : a notion maintained despite evidence to the contrary
Purgatory is a superstition. Prayers to the saints is a superstition. Sola Scriptura is merely a method of discerning the truth by using scripture as the final authority.
You may disagree with it, but it is not a "superstition".
No, Sola Scriptura is a very Scriptural fact, principle, Biblical truth.