I am not sure why you are asking "Are you honestly taking the position that unbelief is not sin?" I know you will be able to explain why you have the right to ask the question, but it appears that you are merely being contentious in asking. Of all the things I have recently posted on this topic zeroing in on this seems trivial.
But to answer the question to clear up the record for you and anybody else that would have ever seriously considered asking, unbelief is sin. My point in saying "it is not sin that makes us lose our salvation" is that there are false teachers out there saying you lose you salvation if you "sin". As you are very aware, there are true, weak believers out there that are in fear of God's love and forgiveness due to them stumbling in any way.
They need to be reminded that they have an advocate:
I John 2:1 "My little children, these things write I unto you, that ye sin not. And if any man sin, we have an advocate with the Father, Jesus Christ the righteous: 2 And he is the propitiation for our sins: and not for our's only, but also for the sins of the whole world."
I John 2:12 "I write unto you, little children, because your sins are forgiven you for his name's sake."
Your use of "Does not Scripture state that “ANYTHING not of faith IS sin?” is not helpful in this context. The previous verse makes it clear that it is not God that condemns him, rather it is himself .
HP asked "Was the death of Christ unable to succor that for which it was intended, or is double jeopardy in play?" This reminds me of the poll about the 10 Commandments. It is obviously neither and the question appears to be loaded. Christ died to gain victory over death. He did that, and I know thatit is no longer my enemy.
I Cor. 15:36 Thou fool(Paul's words, not mine :thumbs: ), that which thou sowest is not quickened, except it die:
So in reality death is something to look forward to by believers. Paul did. If a seed could, it would look forward to being sown even though it were about to die. It would be how it could be changed into a more glorious form.
I Cor. 15:42 So also is the resurrection of the dead. It is sown in corruption; it is raised in incorruption: 43 It is sown in dishonour; it is raised in glory: it is sown in weakness; it is raised in power: 44 It is sown a natural body; it is raised a spiritual body. There is a natural body, and there is a spiritual body. 45 And so it is written, The first man Adam was made a living soul; the last Adam was made a quickening spirit. 46 Howbeit that was not first which is spiritual, but that which is natural; and afterward that which is spiritual. 47 The first man is of the earth, earthy; the second man is the Lord from heaven. 48 As is the earthy, such are they also that are earthy: and as is the heavenly, such are they also that are heavenly. 49 And as we have borne the image of the earthy, we shall also bear the image of the heavenly.
Physical death is nothing to be feared for believers for it the avenue for us to be glorified. No double jeopardy and Christ has defeated death.