"4 For it is impossible, in the case of those who have once been enlightened, who have tasted the heavenly gift, and have shared in the Holy Spirit, 5 and have tasted the goodness of the word of God and the powers of the age to come, 6 and then have fallen away, to restore them again to repentance, since they are crucifying once again the Son of God to their own harm and holding him up to contempt. 7 For land that has drunk the rain that often falls on it, and produces a crop useful to those for whose sake it is cultivated, receives a blessing from God. 8 But if it bears thorns and thistles, it is worthless and near to being cursed, and its end is to be burned."
Hebrews 6:4-8
This passage is, by common consent, one of the most difficult in the entire epistle, if not the whole New Testament. Several interpretations have been offered in explanation of the solemn, frightening words. One is to take it as referring to the possibility of a man who has been truly saved falling away again and being eternally lost. But this would be to contradict the whole weight of evidence in the Scriptures that salvation is forever and cannot be lost or forfeited, Everlasting life would not be everlasting if it could be interrupted by anything whatsoever. When a man is in Christ he is a new creation, and the new creation, unlike the old, does not pass away. God elects men from all eternity, and in Christ we are predestinated from before the foundation of the world to inherit eternal life. It is unthinkable that such roots could ever be plucked up. We take first, then, a word of encouragement and assurance from this passage, and especially offer it to sensitive souls for whom such words are invariably a source of terror and anxiety. We refer to those who have dread of having committed the unpardonable sin. If salvation is forever, then a true believer cannot commit the unpardonable sin. And those most frightened about this are the very least likely to have done so. Take comfort, troubled one, if this is your secret dread, for it cannot apply to you.