Hebrews 6

4 It is impossible for those who have once been enlightened, who have tasted the heavenly gift, who have shared in the Holy Spirit, 5 who have tasted the goodness of the word of God and the powers of the coming age — 6 and then have fallen away — to be restored to repentance, because they themselves are crucifying the Son of God all over again and subjecting Him to open shame.