Bill, the book of Hebrews completely destroys your OSAS foundation, causing it to crumble.
I’ve often heard it said that the doctrine taught in Hebrews is only for the Jews. That’s bull crap. Christians have no problem accepting the blessings given in the book, (intercessory prayers of Christ, supernatural faith, divine provision, access to the throne of grace, etc.). If one aspect of Hebrews is to be applied to Christians, then so should the "whole counsel" of the book.
Some scriptures that comes to mind is Hebrews 6:4-8 (KJV)
(4) For it is impossible for those who were once enlightened, and have tasted of the heavenly gift, and were made partakers of the Holy Ghost,
(5) And have tasted the good word of God, and the powers of the world to come,
(6) If they shall fall away, to renew them again unto repentance; seeing they crucify to themselves the Son of God afresh, and put him to an open shame.
(7) For the earth which drinketh in the rain that cometh oft upon it, and bringeth forth herbs meet for them by whom it is dressed, receiveth blessing from God:
(8) But that which beareth thorns and briers is rejected, and is nigh unto cursing; whose end is to be burned.
It is apparent that this is speaking of a BELIEVER!!! Notice it says "once enlightened", "tasted of the heavenly gift" "were made partakers of the Holy Ghost". You cannot partake of the Holy Ghost by merely attending church, taking communion, being baptized, etc.. You are only a partaker of Him, when He is in you! He has "tasted" the word of God, and enjoyed the "powers of the world to come".
It would be impossible for an unbeliever to be given this privilege by God! Do you know of any unbeliever/sinners who have enjoyed the powers of the world to come?