The awful sin here referred to in verse 26 is not moral sin. It is neither the trespass which overtakes a man, as in Gal 6:1, nor the grievous sin which required the ultimate discipline as in 1 Cor. 5:9-13. It is the sin of apostasy. It is the crime of rejecting revealed truth in a willful, deliberate manner. Apostasy is an abandonment of truth and principles previously professed. The warning of chapter 6 is repeated here. To sin willfully in rejecting the truth and returning to Judaism placed one in an impossible situation. God had rejected the sacrifices of Judaism. The apostate has rejected the sacrifice of Christ. The willful sin of the apostate, once enlightened, left that apostate in a vacuum. He is condemned by his willful rejection of revealed truth. There is only one way for salvation, and it is through the blood sacrifice of Jesus, God’s One of kind Son!