Short Answer
It is a condition that can not actually exist, an absurdity. It is the consequence of an argument presented in the form reductio ad adsurdum, a "reduction to absurdity."
In one of its forms, this type of argument takes a set of premises to its logical conclusion and shows the results lead to an absurdity, thus demonstrating the invalidity of the premises.
A simplification of the argument
It is impossible that someone could be:
- saved 1
- not saved,
- saved again
because Christ would need to be crucified a second time
Detailed Analysis
The Resulting Absurdity
From the ESV:
since they are crucifying once again the Son of God
to their own harm and holding him up to contempt.
This rendering makes better sense of the Greek, clarifying three distinct ideas:
- crucifying once again the Son of God
- holding him up to contempt
- to their own harm
Crucifying once again the Son of God
First, let's establish the absurdity of the idea that Christ's death could be applied more than once:
Heb 9:24-28 (ESV)
For Christ has entered, not into holy places made with hands,
which are copies of the true things, but into heaven itself,
now to appear in the presence of God on our behalf.
Nor was it to offer himself repeatedly, as the high priest enters
the holy places every year with blood not his own, for then
he would have had to suffer repeatedly since the foundation
of the world. But as it is, he has appeared once for all at
the end of the ages to put away sin by the sacrifice of himself.
And just as it is appointed for man to die once, and after that
comes judgment, so Christ, having been offered once to bear the
sins of many, will appear a second time, not to deal with sin
but to save those who are eagerly waiting for him.
This passage demonstrates the following, according to the book of Hebrews:
- Christ does not offer himself repeatedly,
- This would cause him to suffer repeatedly
- He has appeared once for all
- Christ died once to bear sins
- He will appear a second time but not to deal with sin
At this point it should not be necessary to argue this point any further, but may be instructive to recognize the importance of this theme in the book of Hebrews. For those who want to look further:
- Heb 7:27
- Heb 10:1,2
- Heb 10:11-14
To their own harm
If the Son of God were to be crucified a second time, the person responsible would do so to their own harm. A similar argument is given by the author in the following passage:
Heb 10:26-31 (ESV)
For if we go on sinning deliberately after receiving the knowledge
of the truth, there no longer remains a sacrifice for sins, but a
fearful expectation of judgment, and a fury of fire that will
consume the adversaries. Anyone who has set aside the law of Moses
dies without mercy on the evidence of two or three witnesses.
How much worse punishment, do you think, will be deserved by the
one who has trampled underfoot the Son of God, and has profaned the
blood of the covenant by which he was sanctified, and has outraged
the Spirit of grace? For we know him who said, “Vengeance is mine;
I will repay.” And again, “The Lord will judge his people.”
It is a fearful thing to fall into the hands of the living God.
Notice how verse 10:26,27 is almost an exact parallel to 6:4,6.
This similarity in structure can also be seen by rephrasing each passage as:
- If someone goes on deliberately sinning after he was sanctified, there no longer remains a sacrifice for sins, but only fearful expectation of judgement.
- If someone falls away, after sharing in the Holy Spirit, it is impossible to restore him to repentance, because he would crucify Christ again to his own harm.
The second passage contains this warning: The Lord will judge his people, and it is a fearful thing to fall into the hands of the living God. This stern warning instructs the reader how he should take the similar warning in the passage in question.
Holding him up to contempt
Not only does the previous passage state that "deliberately sinning" after being sanctified is tantamount to "trampling the Son of God underfoot," but it would also, "profane the blood of the covenant." Falling away can be described in these same terms. If we were to crucify Christ again, we certainly would be profaning his blood and trampling him underfoot. This is the flavor of "holding him up to contempt."
The Invalid Premises
According to the reductio ad adsurdum argument, these three premises can not be taken as a whole:
Condition 1:
- have once been enlightened
- have tasted the heavenly gift
- have shared in the Holy Spirit
- have tasted the goodness of the word of God
- have tasted the powers of the age to come
Condition 2:
Condition 3:
- restored again to repentance
This can be simplified to the following:
- saved
- not saved,
- saved again
Here is a shortened version of the argument in support of this:
The consequence "since they are crucifying once again the Son of God" is especially instructive for analyzing the premises. Let's start here and work backwards.
First, a keyword is "again." This means Christ's crucifixion has already brought the person in question to repentance once. This is the "hook" of the absurdity in the reductio ad absurdum.
Second, we must establish what Christ's crucifixion accomplishes in the first place. According to Hebrews, the crucifixion accomplishes the following:
- eternal redemption (9:12)
- purifies our consciences (9:14)
- puts away sin (9:26)
- sanctifies once for all (10:10)
- perfects for all time those being sanctified (10:14)
This shows that the premises describe those who were "saved" and then fall into apostasy so that they are "not saved." To double-check this logic, we can do a quick test in which we deny any of these premises and see if the logic holds up. The short version of this is simply to ask, if this is not talking about salvation, how could it result in the absurdity of Christ's death being necessary a second time?
To Believers
There is no argument at all if the author is not talking about salvation. If it is speaking of salvation, then it is a warning to those who are saved. Here are some additional features which support this conclusion:
The passage in question is sandwiched in between statements directed at believers like a parenthetical argument in the middle of a discourse on Melchizedek (5:11 to 6:12). The author opens by stating his desire to "go on to maturity, not laying again a foundation of repentance," and begins to wrap up with the conclusion, "though we speak in this way, yet in your case, beloved, we feel sure of better things--things that belong to salvation." Both the beginning and ending of this parenthetical argument is directed at believers.
A Warning
The rest of the book has numerous warnings about falling away:
- pay much closer attention to what we have heard, lest we drift away from it (2:1)
- how shall we escape if we neglect such a great salvation? (2:3)
- Take care, brothers, lest there be in any of you an evil, unbelieving heart, leading you to fall away from the living God (3:11)
- But if it bears thorns and thistles, it is worthless and near to being cursed, and its end is to be burned. (6:8)
- much less will we escape if we reject him who warns from heaven (12:25)
Conclusion
This is a warning not to fall away from Christ, because there is no second salvation. The absurdity of the necessity arising suggests the conditions are not actually possible, but we can not determine conclusively based on the arguments the author has supplied.
After all, the whole theme of the book is the superiority of Christ and sufficiency of his sacrifice and priesthood. The author doesn't just give his reader warnings, but the converse as well, encouraging them to draw near and actually run toward Christ:
Heb 7:25 (ESV)
Consequently, he is able to save to the uttermost
those who draw near to God through him, since he always
lives to make intercession for them.
and
Heb 12:1,2 (ESV)
Therefore, since we are surrounded by so great a cloud of witnesses,
let us also lay aside every weight, and sin which clings so closely,
and let us run with endurance the race that is set before us,
looking to Jesus, the founder and perfecter of our faith, who for
the joy that was set before him endured the cross, despising the
shame, and is seated at the right hand of the throne of God.
Heb 6:4-8 is the negative side of a dual argument with single goal:
To encourage the believers to remain faithful.
It is the stick that supports the carrot.
1 I support my use of the term "saved" here to mean believers based on the author's use of the word elsewhere, such as "neglect such a great salvation" (2:3), "things that belong to salvation" (6:9), and "he is able to save to the uttermost" (7:5).