Hebrews 10 contains a pretty terrifying warning that has scared a lot of people, myself included:
For if we go on sinning deliberately after receiving the knowledge of the truth, there no longer remains a sacrifice for sins, but a fearful expectation of judgment, and a fury of fire that will consume the adversaries. Anyone who has set aside the law of Moses dies without mercy on the evidence of two or three witnesses. How much worse punishment, do you think, will be deserved by the one who has trampled underfoot the Son of God, and has profaned the blood of the covenant by which he was sanctified, and has outraged the Spirit of grace? For we know him who said, “Vengeance is mine; I will repay.” And again, “The Lord will judge his people.” It is a fearful thing to fall into the hands of the living God. (Hebrews 10:26-31)
This is heavy-duty stuff. No more forgiveness for sins; fearful expectation of judgement; fury of fire consuming adversaries; worse punishment than dying without mercy; God’s vengeful wrath.
What does “sinning deliberately” mean? All of us can think of times we’ve sinned since being saved, sometimes seriously, and often while knowing what we were about to do was wrong. What’s the line? Have we sinned enough to put ourselves in this position?
It’s also puzzling, because in verse 10, he has told us “we have been sanctified through the offering of the body of Jesus Christ once for all” and in verse 14, “For by a single offering he has perfected for all time those who are being sanctified.” Then, we’re told that someone committing this sin was sanctified by Jesus’ blood, but now there’s no more sacrifice for his sin. So which is it? Are we sanctified forever? Or is it possible to do something that puts us forever beyond the reach of grace?
To understand, we must look at the passage in context of the book. Hebrews was written to Jewish Christian converts. They were undergoing severe persecution for their new faith, to the point where many of them were tempted to give up and go back to Judaism.
To encourage them to keep going, the writer of Hebrews shows them how much greater Jesus, his priesthood, his sacrifice, and his covenant are than Moses, the Levitical priesthood, animal sacrifices, and the Old Covenant. Jesus is the High Priest of Heaven, and his sacrifice really takes away sin, unlike the Old Testament system which was merely a shadow of the true reality. In light of this, the author constantly encourages his hearers to not give up, to persevere, and to hold onto the better hope they have in Jesus.
He employs what you could call a “carrot and stick” method; on one hand, there are several warning passages which tell us that since this salvation is so much greater than the law, the consequences for abandoning it are so much greater; on the other hand, the reward we will receive if we persevere, even though we suffer persecution, is worth it.
The sin of Hebrews 10, simply, is the same sin the rest of the warning passages in Hebrews caution against: giving up and abandoning Jesus to go back to a former religion or way of life, because we find following Jesus difficult. If we publicly and deliberately turn our backs on Jesus, there is no remaining sacrifice for sin because Jesus is the only sacrifice for sin. This is not saying that if we sin as a Christian, we will not be forgiven. We know that not to be true from other passages of Scripture (notably, 1 John 1:7-10).
To see this more clearly, let’s look at what the author urges us to do instead, in chapter 10:
Therefore, brothers, since we have confidence to enter the holy places by the blood of Jesus, by the new and living way that he opened for us through the curtain, that is, through his flesh, and since we have a great priest over the house of God, let us draw near with a true heart in full assurance of faith, with our hearts sprinkled clean from an evil conscience and our bodies washed with pure water. Let us hold fast the confession of our hope without wavering, for he who promised is faithful. 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. (10:19-25)
Therefore do not throw away your confidence, which has a great reward. For you have need of endurance, so that when you have done the will of God you may receive what is promised. (10:35-36)
The answer to this terrifying warning is not to cower in fear, thinking that we have somehow been cast away from hope. The answer is to confidently draw near to God in full assurance of faith; encourage each other to love and good works; meet together with other believers; endure knowing we will receive a reward. In short, it’s to hold on to Jesus and not give up, no matter how difficult things get in this life.
Does this passage teach that a person can lose their salvation? That’s a question the Bible doesn’t really ask, or answer. The emphasis of the New Testament is that we are saved if we persevere in faithfulness to Jesus. It also teaches that God’s grace is what enables us to persevere. Whether or not the person who gives up his faith and goes back to a former way of life was ever really “saved” is a meaningless and unanswerable question. We are saved if we hold on to Jesus till the end. The writer to the Hebrews is encouraging us to do that.