Hebrews 6:4-6

It is impossible for those who have once been enlightened, who have tasted the heavenly gift, who have shared in the Holy Spirit,  who have tasted the goodness of the word of God and the powers of the coming age  and who have fallen away, to be brought back to repentance. To their loss they are crucifying the Son of God all over again and subjecting him to public disgrace.