Hebrews 6:4-6 (NKJV)

4 "For it is impossible for those who were once enlightened, and have tasted the heavenly gift, and have become partakers of the Holy Spirit,"
5 "and have tasted the good word of God and the powers of the age to come,"
6 "if they fall away, to renew them again to repentance, since they crucify again for themselves the Son of God, and put Him to an open shame. "