“For it is impossible for those who were once enlightened, and have tasted of the heavenly gift, and were made partakers of the Holy Ghost,”
King James Version (KJV)
6:4 It is impossible for those who were once enlightened - With the light of the glorious love of God in Christ. And have tasted the heavenly gift - Remission of sins, sweeter than honey and the honeycomb. And been made partakers of the Holy Ghost - Of the witness and the fruit of he Spirit.
Heb 6:4 For [it is] impossible. There are sins that have no forgiveness (Mt 12:31,32). There are Apostates who can never find a place for repentance, not because of the failure of God's mercy, but because they have destroyed their moral capacity for a heartfelt repentance. Usually the most hardened sinner are apostates. Those who were once enlightened. Had the light of the Gospel. See Joh 8:12. Have tasted. Experienced. Of the heavenly gift. The new life in Christ. Christ "giveth life unto the world" (Joh 20:31). And were made partakers of the Holy Spirit. The Spirit of God is sent into the heart of all sons (Ga 4:6 Ro 8:9).