No it is not my opinion, it is a FACT! Sola Scripture is not biblical and not even taught in Scripture. It is your opinion to believe otherwise. I recommend you get out of your comfort zone and read early church history.
Here is the truth of your condition or bias toward Scripture. You have either not read the Bible, particularly the Psalms and the words of Jesus or you have read them, but are unable to comprehend them…that is factual; otherwise you would see that Sola Scripture is not only taught by Jesus, the Apostles and the prophets, but by all the writers and the earliest church and many of the 1-3 generation church fathers, but your traditions have done to you what they have done to the Pharisees in my opinion.
Look at what the Bible says in regards to the Scriptures and compare that to the “traditions of the elders”; which negated the spirit of truth found in the what? Scriptures. Do you know that in the OT when you see the phrase “the law and the prophets” it is synonymous with “the Scriptures” and the phrase “it is written” also.
Where did God say there would be “extra Biblical revelation or teachings” outside of the Scriptures that we should follow? That will lead to salvation? That speaks of the Lord and savior? That will teach obedience?
You should do a comparative study on the history of the Jews by comparing and contrasting what God gave concerning the law and the prophets and how they added tons of traditions that violated, voided and condemned so many souls, which Jesus personally stated as much. Why? Their traditions were outside of the spirit of the Scriptures.
What does God say about Israel’s errors; that we are to learn from them so as not to repeat them. If a person does not get rid of all their self righteousness and sin baggage before the Lord, they will not enter into the Kingdom. If you think you can do a ritual or a work and merit saving grace, then you are self righteous according to Biblical standards. Grace is unmerited favor bestowed upon the person who recognizes that there is nothing in themselves or nothing they can do to make things right with God; you are left totally “naked” before Him and must beg for forgiveness and see His perfection against your sinful abased self and give it all up and trust Him, not by the externals, but from the internal, the heart.
This is why He has said that few find the narrow gate and in Luke, those that do at least find it are unable to enter? Why? They come on their own understanding and their own terms of what is right and not by his pure grace, mercy and faith in the promises through Jesus who is the only way to become righteous in His sight.
Those passages in Matthew 7 and Luke 13 should scare everyone who names the name of Christ to death; it is serious and there are just a few just as with Israel there was only and always a remnant; the rest perished in their sins. Jesus said it so plainly, deny yourself, pick up your cross and follow me…that is dying to self and living to Christ.