Seeing then that we have a great high priest, that is passed into the heavens, Jesus the Son of God, let us hold fast our profession.
Seeing then ... - resuming Hebrews 2:17.
Great - as being 'the Son of God, higher than the heavens' (Hebrews 7:26): the archetype and antitype of the legal high priest.
Passed into the heavens, х dieleeluthota (G1330) tous (G3588) ouranous (G3772)] - 'passed through the heavens;' namely, those which come between us and God, the aerial heaven, and that above the latter containing the heavenly bodies, the sun, moon, etc. These heavens were the veil which our High Priest passed through into the heaven of heavens, the immediate presence of God; just as the Levitical high priest passed through the veil into the holy of holies. Neither Moses nor even Joshua could bring us into this rest; but Jesus, our Forerunner, already spiritually, hereafter in actual presence, body, soul, and spirit, brings His people into the heavenly rest.
Jesus the antitypical Joshua (Hebrews 4:8) Jesus - the antitypical Joshua (Hebrews 4:8).
Hold fast - the opposite of "let ... slip" (Hebrews 2:1) and "fall away" (Hebrews 6:6). As the genitive follows, it is, ' let us take hold of our profession;' i:e., of faith and hope, the subjects of our profession х kratoomen (G2902) tees (G3588) homologias (G3671)]. The accusative follows when the sense is "hold fast" (Tittmann).