Imprimatur on what? The RSV translation of Hebrews 10:14-39? Because I went to your link, and entered the reference to the passage in question, and all I got was the Biblical text. Now that is not what we are asking for. We have the text. What we need to know is what is the official Roman interpretation. Back at
post 177, MHGinTN offered an interpretation that is excellent, and accords well with my own belief on the matter.
Simply put, Paul there is describing the cessation of the Mosaic system of sacrifice, and if those Jews who had come to be among the Christians for a while, and had ample evidence of the truth of the faith, but at some point couldn't put up with the persecution, and opted to return to Judaism, the message is grim. If they go back to the shadow world of Moses, there is no further sacrifice they can look to for forgiveness of sin. Jesus is it. Like the last chance gas station at the edge of the desert, if they miss this, they will not make the crossing.
However, this is not apostasy as defined by the "we'll pencil you in" crowd (like the song says, "there's new name written down in pencil, and it's mine, oh yes it's mine ..."). The idea that one can have all their sins paid for, be sealed by the Spirit of God as a promissory note on our making the whole journey, be predestined by God, elect, determined by God's eternal decree to be sons and daughters unto Him, raised from spiritual death to a new and eternal life in Him, and yet be lost, is an idea not taught in Scripture.
For example, the Apostle John, when given a chance to explain those who have fallen away, does not say they were ever recipients of the new birth, or had the seed of God in them, or had been drawn and taught of the Father, or were in true possession of eternal life as those who believe in Jesus are, all of which he could have said, as those were all identifiers of true salvation he himself raised in other places. Instead, what does he do? How does John explain apostasy?
Little children, it is the last time: and as ye have heard that antichrist shall come, even now are there many antichrists; whereby we know that it is the last time. They went out from us, but they were not of us; for if they had been of us, they would no doubt have continued with us: but they went out, that they might be made manifest that they were not all of us.
(1 John 2:18-19)
So for John, apostasy is revelation of preexisting truth. The antichrists among them left them in order to reveal their true status, not to lose a status they once had, a status that elsewhere we find is permanent because it is in God's hands:
All that the Father giveth me shall come to me; and him that cometh to me I will in no wise cast out. For I came down from heaven, not to do mine own will, but the will of him that sent me. And this is the Father's will which hath sent me, that of all which he hath given me I should lose nothing, but should raise it up again at the last day. And this is the will of him that sent me, that every one which seeth the Son, and believeth on him, may have everlasting life: and I will raise him up at the last day.
(John 6:37-40)
We who believe are gifts the Father gives the Son, and just as the Father has power to give us to Christ, He also has the power to determine that Christ will lose none of us. We are the beneficiaries, but God the Father is the guarantor. That is what makes the conclusion certain. It's not about us. It's about Him.
But what we lack from you is any definitive, guaranteed infallible discussion of what this passage in Hebrews 10 specifically means. It would also be interesting to know the official, infallible, Roman position on 1 John 2:18-19, as shown above. Your link does not point us to such official statements of Rome, Imprimatur not withstanding. If the trumpeter blows with an uncertain sound, who can follow that? (1 Corinthians 14:8)
Peace,
SR