[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 (Hebr. 6:6)

The people spoken of are christians. They:

• have once been enlightened
• have tasted of the heavenly gift
• have been made partakers of the Holy Spirit
• have tasted the good word of God
• tasted the powers of the age to come

The whole context is:

Hebr. 6:⁴For it is impossible for those who were once enlightened, and have tasted of the heavenly gift, and were made partakers of the Holy Ghost, ⁵And have tasted the good word of God, and the powers of the world to come, ⁶If 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. 

The word IF is not in the Greek in verse 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” 

Consider what Adam Clarke wrote about this and the aorist tense:

“And having fallen away” I can express my own mind on this translation nearly in the words of Dr. Macknight: ‘The participles who were enlightened, have tasted, and were made partakers, being aorists, are properly rendered by our translators in the past time; wherefore parapesontas, being an aorist, ought likewise to have been translated in the past time, “HAVE fallen away”. Never­theless, our translators, following Beza*, who with­out any authority from ancient MSS. has inserted in his version the word “if” have rendered this clause, IF they fall away, that this text might not appear to contradict the doctrine of the perse­verance of the saints. But as no translator should take upon him to add to or alter the Scriptures, for the sake of any favourite doctrine, I have trans­lated parapesontas in the past time, “have fallen away” according to the true import of the word, as standing in connection with the other aorists in the preceding verses.

*) Theodore Beza was John Calvin’s successor 

Young’s literal translation reads: “And having fallen away, again to renew them to reformation, having crucified gain to themselves the Son of God, and exposed to public shame” (v. 6).

(I can add that the word IF is not present in the common Swedish Bibles so I didn’t have to write all this stuff  about the added word IF when I wrote the equivalent post in Swedish.)

There are a couple of suggestions why the christians in Hebr. 6:6 could not be restored to salvation even though the rest of the Bible provides examples of people who have repented and were brought back to life (for example when Peter sinned by denying Jesus).

1) They might have ended up with a reprobate mind, as in Romans 1 

Rom. 1:²¹ Because that, when they knew God, they glorified him not as God, neither were thankful; but became vain in their imaginations, and their foolish heart was darkened.—²⁴ Wherefore God also gave them up to uncleanness through the lusts of their own hearts, to dishonour their own bodies between themselves:—²⁶ For this cause God gave them up unto vile affections: for even their women did change the natural use into that which is against nature:—²⁸ And even as they did not like to retain God in their knowledge, GOD GAVE THEM OVER TO A REPROBATE MIND, to do those things which are not convenient

The above concerns people who have no excuse for rejecting God since he has clearly been seen and understood by them through his creation. Because they refused to glorify God and instead pursued sin, God gave them over to a reprobate mind and then they were totally absorbed in their vain life styles and were totally lost. People can harden their hearts to the extent that there is no return.

Acts 17:30 And the times of this ignorance God winked at; but now commandeth all men every where to repent

Acts 11:18 When they heard these things, they held their peace, and glorified God, saying, Then hath God also to the Gentiles granted repentance unto life.

If God no longer calls/draws people through the Holy Spirit, and no longer grants people repentance, then people will be for ever separated from God.

2) It could be the unpardonable sin that is spoken about

Those addressed were Hebrew Christians, who were tempted to return to Juda­ism.

Hebr. 10:²⁸ He that despised Moses’ law died without mercy under two or three witnesses:²⁹ Of how much sorer punishment, suppose ye, shall he be thought worthy, who hath trodden under foot the Son of God, and hath counted the blood of the covenant, wherewith he was sanctified, an unholy thing, and hath done despite unto the Spirit of grace?

Mark 3:²² And the scribes which came down from Jerusalem said, He hath Beelzebub, and by the prince of the devils casteth he out devils. ²³ And he called them unto him, and said unto them in parables, How can Satan cast out Satan?—²⁸ Verily I say unto you, All sins shall be forgiven unto the sons of men, and blasphemies wherewith soever they shall blaspheme²⁹ But he that shall blaspheme against the Holy Ghost hath never forgiveness, but is in danger of eternal damnation.

Before being received again into the synagogue they would have to announce publicly that Jesus was not the Son of God; that His blood would not be able to save anyone; and that His miracles were done by the power of the devil. Before their con­version they had belonged to the nation which had crucified Christ; to return to the synagogue would be to crucify to themselves the Son of God afresh and put Him to an open shame; it would be the awful sin of apostasy.

If one accepts this interpretation then he can better understand why those in Heb. 6:4-6 who fell away (parapesontas) could not be renewed by repentance unto salvation as they were enemies of God (10:29), but others, like Peter, who didn’t sin to that degree, could be renewed. The word in this verse translated fall away (parapesontas) is found only once in the NT and that is here!

Moreover, Peter and the other apostles fell away (skandalizo) (Mt. 26:31,33) and perhaps multitudes like them throughout the centuries, but it is not the same Greek word. Jesus taught that blasphemy against the Holy Spirit is directly related to saying that the Lord had an evil spirit by which he was driving out demons. Hence, a link seems to exist between eternal sin and openly insulting the Spirit of grace (Hebr. 10:29). This could possibly explain why the ones referred to in 6:6 could not be renewed unto salvation.

We already know from numerous examples in the Bible that a sinner CAN be renewed and cleansed from his sins, if he confesses his sins and repents, but no one can be forgiven for the unpardonable sin.