WILLFUL SIN AFTER RECEIVING THE KNOWLEDGE OF THE TRUTH 2

26 FOR IF WE SIN WILLFULLY AFTER WE HAVE RECEIVED THE KNOWLEDGE OF THE TRUTH, THERE NO LONGER REMAINS A SACRIFICE FOR SINS,
27 but a certain fearful expectation of judgment, and fiery indignation which will devour the adversaries.
28 Anyone who has rejected Moses’ law dies without mercy on the testimony of two or three witnesses.
29 Of how much worse punishment, do you suppose, will he be thought worthy who has trampled the Son of God underfoot, counted the blood of the covenant by which he was sanctified a common thing, and insulted the Spirit of grace?"
Hebrews 10:26-29 (NKJV)

The description of a believer being addressed in our main text is found in Hebrews 6:4-8
4 FOR IT IS IMPOSSIBLE FOR THOSE WHO WERE ONCE ENLIGHTENED, and HAVE TASTED THE HEAVENLY GIFT, and HAVE BECOME PARTAKERS OF THE HOLY SPIRIT, 5 and HAVE TASTED THE GOOD WORD OF GOD AND THE POWERS OF THE AGE TO COME, 6 if they fall away, to renew them again to repentance, since they crucify again for themselves the Son of God, and put Him to an OPEN SHAME.

A believer who does not fit into the description found in verses 4 and 5 of the above passage is not being referred or talked to in the text of this teaching.
Let us highlight the description of a believer whom if he or she sins willfully which Jesus' atonement or sacrificial death as said in 1 John 1:9 and 2:1 could not suffice or be enough for their sins, according to that Hebrews 10:26:
I. Such a believer should be one who is already enlightened (Hebrews 6:4). It means a believer who can differentiate between his or her left hand from the right—one who can discern both good and evil (Hebrews 5:14).
II. One who has tasted the heavenly gift and has been a partaker of the Holy Spirit (Hebrews 6:4). The word gift there in the verse is gratuity or dividend, favour or reward. In other words, it should be someone who has received God's gift, dividend, favour or reward. And, also such a believer must be a partaker—the word partaker means sharer or associate or partner—of the Holy Spirit. It thus means someone who has tasted heavenly reward and has been a sharer or associate of the Holy Spirit, one who has intimacy with the Holy Spirit—if such willfully committed sins, there would be no more sacrifice for his or her sin.
III. One who has tasted the good Word of God (Hebrews 6:5). The word good in the passage is "kalos" in Greek, and it means properly beautiful or valuable or virtuous or better fair good. It means the believer should be one who has tasted and has had a proper knowledge of the Word of God.
IV. One who has tasted the powers of the age to come (Hebrews 6:5). The Word translated powers in that verse is "dunamis" in Greek and it means miraculous power; a miracle itself or wonderful work. In other words, the believer must be someone who has experienced a miracle or wonderful work of God.
With the illustration here, a believer who has experienced all the points highlighted above is not a novice or a new convert in the Christian faith—such must be a mature believer who knows what he or she is doing.

Thus, our text says If such a believer willfully or intentionally committed sins or renounced Christ Jesus or what he or she believes, there is no remission or atonement or pardon for such a person's sin—the sacrificial death of Christ Jesus does not cover such a person's sin (Hebrews 10:26).
Such a person should expect fearful judgement of God coupled with the indignation which is meant for the adversaries—the word adversaries there means opponents, those who opposed God (Hebrews 10:27). The devil is the main adversary but whoever joins his camp would receive the same judgement that would be meted out to the devil. Hell fire was primarily meant and prepared for the devil, not for human beings, but as many who would not be on God's side, through Jesus Christ, would also be sent to the hell fire alongside with the devil and his angels (Matthew 25:41).

The writer of the passage of our text, the Book of Hebrews, uses the old testament pattern of judgement as an illustration, against whoever rebelled and rejected the law given by God through Moses His servant—that whoever is found guilty, on the testimony of two or three witnesses shall be put to death without mercy (Deuteronomy 17:2-6; 19:15; Hebrews 10:28).
Then, He hypothetically or rhetorically asked: How much worse punishment would they think would be appropriate or proper for whoever trampled the Son of God underfoot (Hebrews 10:29).
This shows that a mature believer, who can discern between good and evil, who willfully committed a sin is:
a. Trampling the Son of God, Jesus Christ, underfoot (Hebrews 10:29).
b. Counting the blood of the covenant by which he was sanctified a common thing (Hebrews 10:29).
c. Insulting the Spirit of grace (Hebrews 10:29).

Note in conclusion:
The Book of Hebrews was written to the believers who left Judaism for Christianity and were being heavily persecuted and they were contemplating of going back into Judaism. Now, consider these points:
I. If you are a believer who is not yet matured, but found yourself in one sin or another every now and then; if you did come to God in repentance, you will be forgiven (1 John 1:9; 2:1,2).
However, God would not want you to remain in that state of rising and falling in sins, every now and then. God would rather want you to be serious with your Christian life, your relationship with Him, and mortify your flesh (Colossians 3:5,6).
It is your personal responsibility to do that—mortify or silence or put to check or control of your flesh—no one will do it for you. If however after a period of time, you refused to change and mortify your flesh, God would begin to chastise or sanction you whenever you committed any sin. And as you continue in Christian journey, If you are yet changed, He would be severer in the discipline or chastisement until a desired change is seen in your life.

II. A mature believer, someone who fits into the description of the Bible passage shared in this teaching, Hebrews 6:4,5, who wilfully committed sins would be left to himself and be doomed.
It is only few people who are found in this category. In other words, It only few believers who have gotten to the level described that could be found to take such a step, renouncing Christ Jesus, God.
Most believers in the category described in the passage are usually ministers of God. But we have seen some who rose to such a level that eventually renounced Christ Jesus, God. We share this that you might be circumspect: "THEREFORE LET HIM WHO THINKS HE STANDS TAKE HEED LEST HE FALL" (1 Corinthians 10:12 NKJV).
Peace.