Hebrews Chapter 6

Therefore let us leave the elementary doctrine of Christ and go on to maturity, not laying again a foundation of repentance from dead works and of faith toward God. For it is impossible, in the case of those who have once been enlightened, who have tasted the heavenly gift, and have shared in the Holy Spirit, to restore them again to repentance. We have this as a sure and steadfast anchor of the soul, a hope that enters into the inner place behind the curtain.