Hebrews 6:4-8

For [it is impossible to restore to repentance] those who have once been enlightened [spiritually] and who have tasted and consciously experienced the heavenly gift and have shared in the Holy Spirit, and have tasted and consciously experienced the good word of God and the powers of the age (world) to come, and then have fallen away—it is impossible to bring them back again to repentance, since they again nail the Son of God on the cross [for as far as they are concerned, they are treating the death of Christ as if they were not saved by it], and are holding Him up again to public disgrace. For soil that drinks the rain which often falls on it and produces crops useful to those for whose benefit it is cultivated, receives a blessing from God; but if it persistently produces thorns and thistles, it is worthless and close to being cursed, and it ends up being burned. [Gen 3:17, 18]