There is a verse in the book of Hebrews which should strike fear into the heart of all Christians who sin. "For if we sin deliberately after receiving the KNOWLEDGE OF THE TRUTH, there no longer remains a sacrifice for sins, but a fearful prospect of judgment, and a fury of fire which will consume the adversaries" (Heb 10:26-27).
The author was saying that Christians should be sure to gather together and exhort each other (v.25) because if they were to sin willfully after receiving "the knowledge of the truth" their only prospect was "judgment and a fury of fire.”
If we dip beneath the surface of the English translation, we quickly discover that it is not just knowledge (Gk gnosis), rather, it is epi – gnosis. The Greek preposition "epi" is an intensifier which, when combined with gnosis "always refers to knowledge which very powerfully influences the form of religious life" and implies a "full" knowledge. Standard reference works explain epignosis in this way: Strong's Dictionary of the NT 1922, epignosis – recognition, i.e. (by implication) full discernment, acknowledgment; Thayers Lexicon 1922, epignosis – precise and correct knowledge; used in the New Testament, of the knowledge of things ethical and divine. If you apply those definitions to "knowledge of the truth" we see that it refers to a full and CORRECT knowledge of things ethical and divine which in turn influences ones religious life.
Vines expository dictionary agrees: 2. epignosis 1922,.denotes "exact or full knowledge, discernment, recognition," and is a strengthened form of No. 1, [gnosis] expressing a fuller or a full "knowledge," a greater participation by the "knower" in the object "known," thus more powerfully influencing him.
The author of Hebrews was pronouncing a dreadful warning to those who had received this "epignosis of the truth". The warning was: "sin deliberately and there would be no more hope, only the prospect of judgment." So, if epignosis refers to full and complete knowledge of the truth, what is "the truth"?
There are two things which come to mind when we see the term "the truth" (not simply truth, but THE truth). 1. Jesus, who is referred to as "the truth." "I am the way, the truth and the life." (John 14:6). 2. The law of God, which is "the truth." "Thy law is the truth" (Psalm 119:142). The law of God and Jesus are forever intertwined. If you know Jesus, you keep the commandments of God. And conversely, if you keep the commandments of God, you know that you have come to know Jesus.
Not true you say? Argue with the apostle John. "And by this we know that we have come to KNOW Him, if we keep His commandments” (I John 2:3). "The one who says, I have come to KNOW Him, and does not keep His commandments, is a liar, and THE TRUTH is not in him” (I John 2:4).
The term "knowledge of the truth" is used elsewhere by Paul, and if we look at those verses they will help us to understand what this enigmatic phrase really means.
Titus 1:1: Paul, “a servant of God and an apostle of Jesus Christ, to further the faith of God's elect and their KNOWLEDGE OF THE TRUTH which accords with godliness.” In this verse we see that it is the "elect" who have the "knowledge of the truth,” and we see that the knowledge of the truth has to do with godliness.
The word "elect" in the Greek text is a form of eklektos which is sometimes translated as "chosen" as indicated by Strong's Greek Dictionary: 1588 eklektos: select; by implication, favorite: KJV – chosen, elect.
It is important to understand this because, according to Paul, it is the chosen (elect) who have the knowledge of the truth. In the gospel of Matthew, Jesus used the same word eklektos when He said: “For many are called, but few are CHOSEN" (Matt. 22:14).
If you refer to the definition of eklektos you will see that Jesus was saying that many are called, but few are selected. That is, many are called by the Father – but only a few are "elect". Many Christians have been called by God and given the gift of faith, but not all of them will be selected (chosen) by God to receive eternal life. Those who are chosen are those who have received the knowledge of the truth ("the elect and their knowledge of the truth." Titus 1:1 above).
Peter also referred to this process of calling and choosing when he said: "Therefore, brethren, be all the more diligent to make certain about His CALLING and CHOOSING you; for as long as you practice these things, you will never stumble” (II Peter 1:10). Was Peter really talking about salvation? The next verse makes it absolutely clear that he was, "for in this way the entrance into the eternal kingdom of our Lord and Savior Jesus Christ will be abundantly supplied to you” (v. 11).
That is why the author of Hebrews warned the Christians to make sure that they continued to gather together and exhort each other about love and good works, because if those who had come to the knowledge of the truth were to "sin deliberately,” they could be certain of "a certain fearful looking for of judgment and fiery indignation, which shall devour the adversaries."
Why are those who have "received the knowledge of the truth" and then "sin deliberately" punished so severely? "How much worse punishment do you think will be deserved by the man who has spurned the Son of God, and profaned the blood of the covenant by which he was sanctified, and outraged the Spirit of grace?” (Heb. 10:2) Because, after receiving the "full and correct" knowledge of the truth, they have spit upon the blood of the covenant by which they were sanctified and outraged the Spirit of grace by rejecting obedience to God's law and deliberately committing sin.
Peter said this about Christians who have come to the knowledge (epignosis) of Jesus and have known the way of righteousness and then turn back to committing sin. "For if, after they have escaped the defilements of the world through the KNOWLEDGE OF THE LORD and Saviour Jesus Christ, they are again entangled therein and overcome, the last state is become worse with them than the first. For it were better for them not to have KNOWN THE WAY OF RIGHTEOUSNESS, than, after knowing it, to turn back from the HOLY COMMANDMENT delivered unto them" (II Peter 2:20-21).
Like the dog returning to its vomit these people escaped the defilements of the world and ceased from sin through the KNOWLEDGE of Jesus (The Truth) and then turned back to sin. They had KNOWN the way of righteousness (the truth) and then chose to "sin deliberately" and break one of the holy Commandments of God. "It has happened unto them according to the true proverb, the dog turning to his own vomit again, and the sow that had washed to wallowing in the mire.” The dire warnings found in Peter and Hebrews are there for our protection. If the reader is a Christian who is still committing sin by deliberately breaking any of the Ten Commandments and is anxious to repent, let him take heart, for if he is able to repent, then he is not one who has come to a knowledge of the truth and turned back to sin.
The very fact that one wants to repent is proof that he is still able to be saved, for God has not yet rejected him and sent him a delusion as described in II Thessalonians: "and with all unrighteous deception among those who perish, because they did not receive the love of THE TRUTH, that they might be saved. And for this reason God will send them strong delusion, that they should believe the lie, that they all may be condemned who did not believe THE TRUTH but had pleasure in UNRIGHTEOUSNESS" (II Thess. 2:10-12).
As I sat here pondering how to close, I decided there could be no better way than to simply repeat the words that God inspired in the author of Hebrews as he tried to warn his brethren about the awful consequences of intentional sin: "and let us consider how to stir up one another to love and good works, not neglecting to meet together, as is the habit of some, but encouraging one another, and all the more as you see the day drawing near. For if we sin deliberately after receiving the knowledge of the truth, there no longer remains a sacrifice for sins but a fearful prospect of judgment, and a fury of fire which will consume the adversaries."