A. The prior state of those under discussion is that they had:
1. Been enlightened.
2. Had tasted the heavenly gift. (The word for tasted is γευσαμένους (geusamenous) which means to experience. This is the same word that is used in 2:9 where it speaks of Jesus having "tasted" death for everyone. This is not a mere limited sampling, this is an embracing of the full experience.
3. Been made partakers of the Holy Spirit. These had received the indwelling of the Holy Spirit who serves as the Christian's seal of divine ownership.
4. Tasted the good word of God. Again the same word as in verse 4, γευσαμένους.
B. Present state - They have "fallen away." From what then had they fallen?
1. An enlightened state.
2. The experience of the heavenly gift.
3. The partaking or sharing of the Holy Spirit.
4. The good word of God.
5. They had crucified Christ all over again. Like those of 10:26-31, these had "trampled under foot the Son of God and regarded as unclean the blood of the covenant by which he WAS sanctified" (passed tense). In other words these has come to regard the blood that had once sanctified them as nothing more than the proverbial hog slaughtered on the altar.
C. The impossible dilemma - It is now impossible to renew them again to repentance. Why? Because they have fallen away from the very thing that brought them to repentance in the first place which was the word of God. It is now impossible to restore them to repentance. One cannot be RE-newed AGAIN to a state they have never occupied. Thus, having once been saved and then having fallen away, they cannot be brought back because they will no longer repent. This is of course representing the extreme case.
D. Their fate.
Like the ground that yields thistles and thorns, they are cursed and they end up being burned. Just like those of 10:26-31, whose fate is to fall into the hands of a vengeful God who says, "I will repay." The parabolic illustration come out of Matthew 13:20-21, Mark 4:16-17, and Luke 8:13. They had become worthless to the purposes of God and God discarded them.
1. The writer is not saying that these claimed to have tasted, but presents a simple statement of fact - "They had tasted." Having once shared in the fellowship of Christ these had later abandoned Christ and returned to the law. These had previously left the law in response to the gospel. Now, they are rejecting the cross and going back to the law. This is the foundation they were "laying again."
2. This is not a question. There is no "if" in the Greek. It simply says, παραπεσόντας (parapesontas) - literally "having fallen away". This is a statement of fact based on actual cases, not a what if scenario. This is an aorist, passive, accusative verb. They had fallen away at some time in the past and that condition continues. They are still fallen away. This is the force of the aorist accusative case. At some point in the past they had fallen away - punctiliar action irrespecrtive of the amount of time involved, and they remain fallen away. Their condition has not changed.
3. Under the law, sin was not forgiven based on those sacrifices, but based of what those sacrifices represented - the cross. Leviticus chapters 4 and 5 show us that sin was indeed forgiven under the law but, it was not by the law. Even David understood this. "How blessed is the man whose transgression is forgiven, whose sins are covered...to whom the Lord does not impute iniquity," Psalms 32:1-2. He also knew those sacrifices were not the avenue through which forgiveness came. "Thou dost not delight in sacrifice or I would bring it." Psalms 51:1-2.
4. The inability to renew again is not linked to a supposition of "IF" they were to fall away. The impossibility is linked to the fact that after having been saved they had rejected the cross, not the old sacrifices, and in so doing had shamed Christ openly and defiantly.
5. The writer does not say they could not be saved again. He says that cannot be brought back to repentance again. This certainly renders them unable to remain saved since there is no longer repentance. These had once been in a saved relationship. Now that relationship has been severed; not by Christ but by them.
6. He is not comparing the crucifying of Christ again to the repetitious offering of O.T. sacrifice. Those who had rejected and fallen away were considering Christ worthy of the crucifixion. They were rejecting him and his sacrifice. Like those of 10:29, they were considering the blood of Christ "BY WHICH THEY HAD BEEN SANCTIFIED" an unclean thing, and had insulted the Spirit of grace.
7. The writer's point is that these had been sanctified - made holy - A state given only to the saved, something that all of the sacrifices of the O.T combined could never do. In verse 29, he even draws a contrast between the one's of whom he is speaking and those who died under the law for rejecting Moses. They rejected the blood after having been cleansed by it and are now worthy of greater punishment than those who were under the Law. Verse 30 shows their fate. The Hebrew writer describes both the prior and latter states of those who had fallen away.