falling away

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