The mention of the judgment suggests the dreadful consequences of falling away from faith. It is assumed, as in Hebrews 6:4 ff., that no second repentance is possible. If men persist in sinning after they have once accepted the Christian message, they cannot again expect forgiveness through Christ's sacrifice (Hebrews 10:26). They have nothing to look for now but that condemnation which the Scripture so often threatens when it speaks of the wrath of God that burns like fire (cf. Psalms 79:5; Isaiah 26:11; Zephaniah 1:18; Zephaniah 3:8; Ezekiel 36:5). The punishment of apostasy from the Mosaic Law, when duly proved by two or three witnesses, was death (cf. Deuteronomy 17:6). Must we not believe that something worse than death is in store for those who show open contempt for the Son of God, who regard the blood which He shed to seal the new covenant and give us access to God as nothing more than ordinary blood, who wantonly insult the Spirit from whom proceed all higher gifts? Apostasy from the great Christian privileges enumerated in Hebrews 6:4 f. is held to be equivalent to declaring them worthless and mocking at them. God never threatens in vain, and He has stated that He will inflict punishment on evildoers, and will sift out His true servants from the false (Hebrews 10:30). We have to give account of ourselves to a living God, one who knows everything, and who can execute His will to the uttermost (Hebrews 10:31).
Hebrews 10:29. an unholy thing: lit. a common thing, without any sacred significance (see Exodus 12:22 *).