Hebrews 6:8

but that which beareth thorns and briers is rejected, and is nigh unto cursing; whose end is to be burned.

Here we have the reason why progress and growth cannot be thought of in the case of certain people: For it is impossible that people that have once been enlightened, having tasted as well the heavenly gift and become partakers of the Holy Spirit, and having tasted the excellent Word of God and the powers of the world to come, and then having fallen away, may be renewed unto repentance, because they crucify the Son of God to themselves and hold Him up to shame. This difficult passage must be examined very closely if one wants to grasp the intended meaning. The writer declares that it is a flat impossibility for certain persons to be renewed, to be brought back a second time to repentance. These persons he characterizes by a description involving four points. The people whom he has in mind are such as have been enlightened by the Holy Ghost through the Word, that have a spiritual understanding of Christ and of their redemption through Christ, Ephesians 1:18; Ephesians 5:8; 1 Peter 2:9, in other words, Christians, such as have been called out of the darkness of godlessness to the marvelous light in Christ. The people referred to by the author are furthermore such as have tasted the heavenly gift, the gift of the salvation in Christ as a precious gift of grace, the forgiveness of sins, all the blessings of the adoption of children, peace and joy in the Holy Ghost. They have furthermore become partakers of the Holy Ghost, they have been sealed with the Holy Spirit of promise, the earnest of our inheritance until the redemption of the purchased possession, Ephesians 1:14. They have finally tasted the splendid, the excellent Word of God and the powers of the future life; they feel, they realize, the mighty influence which God's Word of promise exerts upon spirit, mind, and soul. They have experienced the power of God unto salvation, the vehicle of all eternal, heavenly blessings; they have, by faith, anticipated the enjoyment of the life to come, being partakers of the glory of heaven in hope.

If persons to whom this description applies, people that have undoubtedly accepted Jesus as their Savior, placed their trust in His salvation, and anticipated the joys of eternal life by reason of the power given to them through the Word, now fall away in spite of this saving knowledge, by a deliberate denial of that knowledge, then their return to repentance is excluded. The reason for this fact is not to be sought in God, as though His gracious intention and will in their behalf had not been sincere, but in the people themselves. If their apostasy takes place as here described, with a deliberate, malicious denial of the truth, then they crucify to themselves the Son of God and set Him forth to shame and ignominy before men. They purposely and willfully deny all connection with the Lord, who was crucified for them, they brand Him as a criminal, as a false Messiah, who suffered the disgrace of death on the cross. All this they perpetrate against Him whom they formerly acknowledged as the Son of God, whom they knew to be the Savior of the world. They cannot plead ignorance, or that they acted in foolish unbelief. For that reason their behavior brings upon them judgment, eternal condemnation. Therefore the reason why their hearts become hardened, why it becomes impossible for them to return and to be renewed unto repentance, is to be found in the character of their transgression. They steadfastly and persistently persevere in their anti-Christian, blasphemous conduct, they harden their own hearts against all attempts of the Word to find an entrance, and are thus finally given over into their hardness of heart, Acts 28:27.

The writer does not say that his readers have reached this stage; he merely states the possibility that it may happen to them as it has to others, thus warning them to beware of spiritual sluggishness, of lack of diligence in the use of the means of grace. See 2 Corinthians 6:1. And he emphasizes his warning by a parable: For land which absorbs the rain which often falls upon it and brings forth plants that are useful to those that have tilled it partakes of a blessing from God, but that which produces thorns and thistles is worthless and on the verge of a curse, and its end is burning. This is an analogy from nature to illustrate the doom of the apostate. In the case of a piece of ground that responds to the tilling of the farmer or gardener and has a sufficient amount of rain for the crops which have been put in, yielding a harvest in proportion to the expectations which could fittingly be held, God's approval is seen in the rich returns from the soil. But if a piece of ground that has been tilled with all care and gets all the moisture which is needed for a good crop, and yet refuses to respond to such treatment, does not prove worthy, it must be condemned as worthless, and the thorns and thistles which it hears must finally be burned. The application of the parable is not difficult. The abundant and frequently renewed rain represents the free and continued offer and bestowal of God's grace, the enlightenment of the Word of God, the effective working of the Holy Spirit in the hearts of the believers. This should have enabled them all to bring forth proper fruit to God. If, therefore, any persons that have received these blessings harden their hearts and bring forth fruits of blasphemy and malicious denial of grace, they have sealed their own doom. For the behavior here described is the sin against the Holy Ghost, for which there is no forgiveness, neither in this world nor in the world to come. See Matthew 12:31; Mark 3:28; Luke 12:10.