As you have often told us about, your entire view of all scripture, from Genesis to Rev. is fueled by a misinterpretation of, especially, Paul as they wrote God's breath to a world that was steeped in Torah but had never understood anything about the new (to them) Christ. You know little about Torah but in the culture you were raised in, Christ is old and Torah is new. So, as you constantly state, you know all about using Christ but read scriptures about using Christ as only just don't listen to Torah when that is certainly not what scripture says.Where is what you are referring to called a "great mystery?"
You didn't even read Eph, did you?
You don't know the NT very well, do you?
You know all about the word "obsolete". You know thoroughly the book of Hebrews speaking to those who would use only Torah to worship God and leaving out Christ, of using Christ as the High Priest instead of the Levi priesthood. But you are reading it as a person who knows absolutely nothing about using Levi as the priesthood so all your mind absorbs of it is the spirit of negativity. You can't see the Christ it is telling to use, you see only the orders to not use something, and you make those orders into orders not to know anything about what the book of Hebrews depends on you knowing too well and depending on instead of depending on Christ.
Of course, you see people who study the bible as never reading the parts of the bible you do read and believe in! You are sure the bible only tells you what not to study or believe in, and that is not what scripture is telling you at all. You have as great a need of scripture as the Hebrews that the book of Hebrews is speaking to needed scripture. They needed to include Christ when they only had Torah, you need to include the knowledge of Torah to read the book of Hebrews. You are in as great a need as the people the book of Hebrews was written to.
Your entire view of God is wrapped around the words of obsolete, saying all scripture is written to say this has been completed when scripture doesn't say that, around the word fulfilled as a word meaning that when something has reached perfection, anything it was before must be gotten rid of. You have as distorted a view of scripture today as the people who read scripture without knowing and accepting all Christ is had because they had never heard of Christ before and didn't trust who Christ was.