Question: "Does Hebrews 10:26 mean that a believer can lose salvation?"
Answer: “For if we are willfully sinning after receiving the full knowledge of the truth, there remains no more sacrifice concerning sins.” Hebrews 10:26-29 warns against the sin of apostasy. Apostasy is an intentional falling away or defection. Apostates are those who move toward Christ, right up to the edge of saving belief, who hear and understand the Gospel, and are on the verge of saving faith, but then reject what they have learned and turn away. These are people who are perhaps even aware of their sin and even make a profession of faith. But rather than going on to spiritual maturity, their interest in Christ begins to diminish, the things of the world have more attraction to them rather than less, and eventually they lose all desire for the things of God and they turn away. The Lord illustrated these types of people in the second and third soils of Matthew 13:1-9, 18-23. These are those who “receive with joy” the things of the Lord, but who are drawn away by the cares of the world or turned off by difficulties they encounter because of Christ.
“Willful sinning” in this passage carries the idea of consciously and deliberately rejecting Christ. To know God’s way, to hear it preached, to study it, to count oneself among the faithful, and then to turn away is to become apostate. Sinning willfully carries with it the idea of sinning continually and deliberately. Such a person does not sin because of ignorance, nor is he carried away by momentary temptations he is too weak to resist. The willful sinner sins because of an established way of thinking and acting which he has no desire to give up. The true believer, on the other hand, is one who lapses into sin and loses temporary fellowship with God. But he will eventually come back to God in repentance because his heavenly Father will continually woo and convict him until he can’t stay away any longer. The true apostate will continue to sin, deliberately, willingly and with abandon. John tells us that “No one who is born of God practices sin, because His seed abides in him and he cannot sin, because he is born of God” (1 John 3:9).
Apostates have knowledge, but no application of that knowledge. They can be found in the presence of the light of Christ, mostly in the church, among God’s people. Judas Iscariot is the perfect example—he had knowledge but he lacked true faith. No other rejector of the truth had more or better exposure to the love and grace of God than Judas. He was part of Jesus’ inner circle of disciples, eating, sleeping, and traveling with Him for years. He saw the miracles and heard the words of God from Jesus’ very lips, from the best preacher the world has ever known, and yet he not only turned away but was instrumental in the plot to kill Jesus.
Having turned his back on the truth, and with full knowledge choosing to willfully and continually sin, the apostate is then beyond salvation because he has rejected the one true sacrifice for sins: the Lord Jesus Christ. If Christ’s sacrifice is rejected, then all hope of salvation is gone. To turn away willfully from this sacrifice leaves no sacrifice; it leaves only sin, the penalty for which is eternal death. This passage is not speaking of a believer who falls away, but rather someone who may claim to be a believer, but truly is not. Anyone who apostatizes is proving he never had genuine faith to begin with (1 John 2:19).