The book of Hebrews which is seen as so harsh by so many – Martin Luther even wanted it removed from the cannon – is all about grace. The problem with our understanding of the book of Hebrews, and what causes it to be so harsh, is that it lacks the one-step-back theology* that we love. I do believe this is on purpose because of its intended audience. An analogy might be drug usage. When parents talk to their children about drugs, they talk to them about the dangers, the consequences and worst-case scenarios. Parents tell their children how a single use of drugs can kill them or cause them to be hooked for life. They tell them about how many lives have been destroyed, and omit the possibility of it being anything else. So it is with Hebrews.
Hebrews is a letter written to a church under attack. It was not the frontal attack of the government, capturing and killing them, but the insidious attack of the Sadducees and Pharisees, driving them out of the temple by including phrases in the daily prayer that made Christians curse themselves if they participated, and other such changes to their religious practices.
Unlike Americans, the Jews of this era, and possibly all eras, saw themselves in relationship to the community. They would not have believed that participating in all of the prayer except that portion that cursed them would be acceptable. Standing in the temple during the prayer would be the same as saying and agreeing with that prayer. Not just part of the prayer, but all of the prayer. So the book of Hebrews was written to a group that was choosing whether or not to follow Jesus or to turn back to the old ways.
The choice being made was not a simple one. It was like the drug analogy where once the choice was made the consequences were inevitable. The author purposely left out the one-step-back theology just like parents leave out the possibility of not having major negative consequences for drug usage.
Understanding that Hebrews is not negating one-step-back theology but rather highlighting the severity of the circumstances that the readers were in allows us to see what the author was trying to point out which was the supremacy of Christ, the value of our salvation and the need to stand firm.
Our ability to stand firm is all because of grace by which we enter God's rest.
*The belief that taking one step toward God, through the acts of confession and repentance restores your right standing before God.