ISB ~ Hebrews 6 v4

enlightened:Perhaps a reference to Baptism, which was called “enlightenment” in early Christian times. This developed from the notion that incorporation into Christ, which is the effect of Baptism (Rom 6:3; Gal 3:27), is described in the NT as an enlightening of the believer (2 Cor 4:6; Eph 5:14; 1 Pet 2:9) (CCC 1216).

• We are enlightened when we are baptized. The rite is called enlightenment since by it we behold the holy light of salvation, that is, we come to see God clearly (St. Clement of Alexandria, Christ the Teacher 1, 6, 26).

heavenly gift:Probably a reference to the Eucharist. The life-giving humanity of Jesus received in the sacrament is the Father’s gift of manna from heaven (Jn 6:32-58).

partakers of the Holy Spirit:i.e., sharing the indwelling presence of the Spirit (Acts 2:38; Rom 8:11) and endowed with his spiritual gifts (Heb 2:4; 1 Cor 12:4-11).