Hebrews 6:1Therefore let us leave the elementary teachings about Christ and go on to maturity, not laying again the foundation of repentance from acts that lead to death,[a] and of faith in God, 2instruction about baptisms, the laying on of hands, the resurrection of the dead, and eternal judgment. 3And God permitting, we will do so.

4It is impossible for those who have once been enlightened, who have tasted the heavenly gift, who have shared in the Holy Spirit, 5who have tasted the goodness of the word of God and the powers of the coming age, 6if they fall away, to be brought back to repentance, because[b]to their loss they are crucifying the Son of God all over again and subjecting him to public disgrace.

Some confusion in the Letter to the Hebrews exists among Christians. Understanding that this letter is written to “Hebrews” clears the air. The letter has 12 subjects Jewish Christians needed to see. For example, the letter starts with angels in Chapters 1 and 2, and leading through Moses, Worship, Sacrifices and finally Personalities and the New “Laws” Jewish Christians could see how the old way was inferior to the new work of God in Jesus Christ on the cross.

The Jewish nation had received every teaching, prophecy and blessing necessary to know about repentance and God’s love, forgiveness and sacrificial system (compare Rom. 9:4), yet when Jesus came along most Jews rejected him. The official Jewish hierarchy rejected him.

So, in Chapter 6, where much of the confusion exists for Christians, the “elementary teachings” were the teachings of Judaism not of Christianity. Paul confirms these are not for Christians in 6:9. The Jewish readers have received “better things”. Many Jews had committed the unpardonable sin, that is, the blasphemy against the Holy Spirit who filled Jesus and spoke to them about his true identity and purpose. They had tasted and shared in his life, but rejected Him or had “fallen away.” Now, decades after Jesus had ascended into heaven, they were unconvinced of the superiority of the New Covenant in Christ alone, so to come back to the truth they had once tasted, but rejected, these Jewish unbelievers would need a new crucifixion as proof. Or, if they did come back it would take another “public disgrace” since they had missed their opportunity.

Paul states the same thing clearly to Gentile Christians in Romans 9:30What then shall we say? That the Gentiles, who did not pursue righteousness, have obtained it, a righteousness that is by faith; 31but Israel, who pursued a law of righteousness, has not attained it. 32Why not? Because they pursued it not by faith but as if it were by works. They stumbled over the “stumbling stone.” 33As it is written:
“See, I lay in Zion a stone that causes men to stumble
and a rock that makes them fall,
and the one who trusts in him will never be put to shame.”

All the confusion about doing the wrong thing and exposing ourselves to God’s rejection is hopelessly tied to confusion about who the Letter of Hebrews is to. The Jewish Nation rejected Jesus once. God cut them off because they were living in his old system, rejecting his new covenantal relationship. Hebrews 6 is not to those who have put their faith in Christ’s death, burial and resurrection (1 Cor. 15:1-7) because …
Romans 8:1Therefore, there is now no condemnation for those who are in Christ Jesus,[a] 2because through Christ Jesus the law of the Spirit of life set me free from the law of sin and death. 3For what the law was powerless to do in that it was weakened by the sinful nature,[b] God did by sending his own Son in the likeness of sinful man to be a sin offering.[c] And so he condemned sin in sinful man,[d] 4in order that the righteous requirements of the law might be fully met in us, who do not live according to the sinful nature but according to the Spirit.