Hebrews 6:4-6

6:4 For it is impossible in the case of those who have once been enlightened, tasted the heavenly gift, become partakers of the Holy Spirit, 6:5 tasted the good word of God and the miracles of the coming age, 6:6 and then have committed apostasy, to renew them again to repentance, since they are crucifying the Son of God for themselves all over again and holding him up to contempt.

Hebrews 10:26-29

10:26 For if we deliberately keep on sinning after receiving the knowledge of the truth, no further sacrifice for sins is left for us, 10:27 but only a certain fearful expectation of judgment and a fury of fire that will consume God’s enemies. 10:28 Someone who rejected the law of Moses was put to death without mercy on the testimony of two or three witnesses. 10:29 How much greater punishment do you think that person deserves who has contempt for the Son of God, and profanes the blood of the covenant that made him holy, and insults the Spirit of grace?