Problem: The author of Hebrews writes, “Christ was faithful as a Son over His house—whose house we are, if we hold fast our confidence and the boast of our hope firm until the end” (Heb. 3:6). Later he writes, “We have become partakers of Christ, if we hold fast the beginning of our assurance firm until the end” (Heb. 3:14). Does this mean that we can lose our salvation from having a hardened heart?
Solution: Verse 6 states clearly that the house refers to Christian believers (“And we are his house” NIV). But the author is referring to the function of the house—not the individual members being a part of the house. This doesn’t refer to our justification. Instead, it refers to our function as the church and our sanctification.
Later the author will say, “We have a great priest over the house of God, 22 let us draw near with a sincere heart in full assurance of faith, having our hearts sprinkled clean from an evil conscience and our bodies washed with pure water” (Heb. 10:21). We have “full assurance” in being a part of Christ.
“Partakers” (v.14) is the Greek word metochoi. BDAG defines this word as “sharing or participating in” or of “business partners and companions.” For instance, Luke uses it in this sense (Lk. 5:7). This refers to participating in Christ’s work—not being sent to hell.
This interpretation fits with the larger context of the Exodus generation forfeiting God’s rest (see comments on Hebrews 3:7-4:11).
1 Corinthians 9:24-27 serves as a parallel, though in the context of the Isthmian Games. It isn’t that we take the place of someone else’s salvation. Instead, this is the imagery of winning the race, and not being cut out of partaking in Christ’s sanctification and work. In 1 Corinthians 10, Paul cites the Exodus generation being “benched” from the games. Spiritual privilege is no certainty for spiritual reward.
“But Christ as a son over his own house; whose house are we, if we hold fast the confidence and the rejoicing of the hope firm unto the end. 14 For we are made partakers of Christ, if we hold the beginning of our confidence stedfast unto the end; (Heb 3:6.14)”