Let’s read Hebrews 10:26-27, “If we sin willfully after we have received the knowledge of the truth, there no longer remains a sacrifice for sins, but a certain fearful expectation of judgment, and fiery indignation which will devour the adversaries” (NKJV). As we shall see, the “sin” in question here is the “sin of apostacy,” which means the “sin of abandoning the Christian faith.” This epistle was written to Jews who had made a profession of faith in Christ but many of them were still “clinging to the Law of Moses” and SOME of them were in danger of going back to offering animal sacrifices for the forgiveness of sins. We read in Acts 21:20, “And when they heard it, they glorified the Lord. And they said to him, ‘You see, brother, how many myriads of Jews there are who have believed, and they are all ZEALOUS FOR THE LAW.” When the “knowledge of the truth” (the gospel of Jesus Christ) was presented to the Jews MANY BELIEVED and were saved, but they were still attending synagogues and going to the temple in Jerusalem. There was a real possibility that SOME who professed to believe had not really believed in Christ as their Savior and as time went on, they were entertaining the idea of renouncing their faith in Christ and returning to the rituals of Judaism to save them. This view is supported as we read on in verses 28-29, “Anyone who has rejected Moses’ law dies without mercy on the testimony of two or three witnesses. 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.” If one would renounce Christ, he would be guilty of “trampling the Son of God underfoot.” In essence he would be saying, “I no longer believe that Jesus Christ is the Son of God and that His death on the cross took away my sins.” This is the SIN OF APOSTACY, the act of denying the faith that you once professed to believe. If a Jew did commit this sin, they are told in verse 26, “there no longer remains a sacrifice for sins.” In other words, Jesus Christ and His death on the cross is the only “sacrifice for sins” that is available for one to be forgiven and if you reject His sacrifice there is “no other sacrifice for sins.” Instead of having a sacrifice for sins, there would be “a certain fearful expectation of judgment.” The one who abandons Christ can only look forward to God’s judgment for their sins since they have rejected the sacrifice of Christ where He endured God’s judgment for sins for everyone who believes. This reminds me of Hebrews 2:2-3, “For if the word spoken through angles proved steadfast, and every transgression and disobedience received a just reward, how shall we escape if we neglect so great a salvation, which at the first began to be spoken by the Lord, and was confirmed to us by those who heard Him.” The obvious answer to this is: There is NO ESCAPING GOD’S JUDGMENT if we neglect (or reject) the salvation He offers to us in Christ and His death on the cross (see John 3:16-18, 36).

As to your second question, LYING is always wrong (see Ephesians 4:25). It is a SIN; in fact, it is indeed a “willful sin.” We know when we are lying for our conscience bears witness to us (see Romans 2:14-15). Yet as we have seen, the sin in Hebrews 10:26 is NOT speaking of “willful sins of immorality” but rather the “willful sin of apostacy.” There are those who believe this verse speaks of “any sin that we willfully commit” but as we have seen the CONTEXT proves that this is the “sin of rejecting Christ and His sacrifice for sins.” The believer in Christ who sins will suffer consequences for sinning, but they will NOT be judged of God for all eternity like the unbeliever will, for “their sins were already judged on the cross when Jesus died for them.” We read in 1^st Corinthians 15:3-4 and 1^st Peter 3:15, “Christ DIED FOR OUR SINS according toe the Scriptures” …For Christ also SUFFERED ONCE FOR SINS, the just for the unjust, that He might bring us to God.” These verses are crystal-clear; Christ’s took the sinner’s place on the cross; He SUFFERED God’s judgment for those sins, and He DIED for those sins. If a believer sins, he loses the “joy of salvation” (see Psalm 51:12) and the “peace of God” (Philippians 4:6-7), but he does NOT lose the forgiveness and salvation he received when he accepted Jesus Christ as his Savior (Acts 10:43; 13:38-39 and 16:31). In order to have his joy and peace restored he must acknowledge his sin and confess it to God the Father, and he will be restored to fellowship with God which brings with it joy and peace. “If we confess our sins, He is faithful and just to forgive us our sins and to cleanse us from all unrighteousness” (1^st John 1:9). This is what we call “paternal (Fatherly) forgiveness” which a “child of God” needs every time he/she sins. But the moment the sinner believes on Christ for forgiveness he/she receives “judicial forgiveness” from a holy and righteous God. That forgiveness only happens ONCE and it results in all of our sins being forgiven (1 John 2:12 with Acts 10:43, Ephesians 1:7 and Colossians 1:14).  (DO)  (503.5)