Heb 10:29 Of how much sorer punishment, suppose ye, shall he be thought worthy,
who hath trodden under foot the Son of God, and hath counted the blood of the covenant,
wherewith he was sanctified, an unholy thing, and hath done despite unto the Spirit of grace?
What is really meant by "sin willfully" in Heb 10:26 ? It points to the three things in Heb 10:29
(1) trodden καταπατέω (Thayer G2662) underfoot the Son of God,
(2) counted the blood of the covenant wherewith he was sanctified as an unholy thing κοινός (Thayer G2829), and
(3) done despite ἐνυβρίζω (Thayer G1796) to the Spirit of grace.
In sum, it means to reject the gospel of salvation, "not" the believers loss of salvation. This person hears the word of
God which states that Jesus is the Son of God, yet he answers by insulting Jesus and to reject Him with disdain and contempt . He has heard God’s word which says that Jesus has shed His blood for the remission of sins and that His blood is most precious—even as the blood of a pure spotless lamb [to sanctify-to make holy], but he replies by saying that the death of Jesus is a martyr’s death and that the blood Jesus shed is common just like anybody else’s. He has heard the word of God which says that the Holy Spirit brings repentance and gives eternal life, nevertheless he retorts by declaring that he does not believe God will impart to him what Jesus has accomplished nor does he believe in new birth. Because of this kind of reaction, the Bible’s word is that there remains to him no more sacrifice for sins.
Hebrews 10 is clear that anyone who has heard the truth and yet has sinned willfully by rejecting the Holy Spirit as well as the blood of the Son of God. For such a person who has despised the Son of God there remains no more sacrifice for sins. For people in the Old Testament time, if they missed the opportunity for atonement one year they still might have it the following year. But today, if any man should reject Jesus Christ, there does not remain anymore sacrifice for sins, since even the sin-offering of the Old Testament dispensation has passed and is therefore no longer effective. Whoever has the knowledge of the truth but rejects it has no more sacrifice for sins available to him. God had done His uttermost when He sent the Lord Jesus Christ to this world to accomplish the work of redemption so that we might be saved. There is therefore nothing more He can add. Accordingly, the Bible tells us that if any man should sin willfully, that is, reject the gospel which he has heard and known, it is finished and done with for him. His end is nothing but a certain fearful expectation of judgment and a fierceness of fire which shall devour the adversaries.
