- For if we sin wilfully after that we have received the knowledge of the truth, there remaineth no more sacrifice for sins, But a certain fearful looking for of judgment and fiery indignation, which shall devour the adversaries. (Hebrews 10:26-27)
Many say this verse proves that we can lose our salvation. I used to believe this, as well. The problem with that interpretation is that if we're to believe it, it also means that, if possible, once we lost our salvation we could never get it back. And that's a point they typically neglect to point out.
Another interpretation is that it's absolutely true, there is no more sacrifice for sins after we sin willfully. But that does not mean Jesus Christ's sacrifice is insufficient to cover our sins. Believers are still going to heaven and still have Christ's righteousness imputed to their account.
As for the second part, there remain earthly consequences for the believers' sins, and I believe that addresses the fearful looking for judgement and fiery indignation:
- And ye have forgotten the exhortation which speaketh unto you as unto children, My son, despise not thou the chastening of the Lord, nor faint when thou art rebuked of him: For whom the Lord loveth he chasteneth, and scourgeth every son whom he receiveth. If ye endure chastening, God dealeth with you as with sons; for what son is he whom the father chasteneth not? But if ye be without chastisement, whereof all are partakers, then are ye bastards, and not sons. Furthermore we have had fathers of our flesh which corrected [us], and we gave [them] reverence: shall we not much rather be in subjection unto the Father of spirits, and live? For they verily for a few days chastened [us] after their own pleasure; but he for [our] profit, that [we] might be partakers of his holiness. Now no chastening for the present seemeth to be joyous, but grievous: nevertheless afterward it yieldeth the peaceable fruit of righteousness unto them which are exercised thereby. (Hebrews 12:5-11)
That said, the most contextual interpretation that I see is that this message was to the Jews (who learned about Jesus and what He did) and was warning them that they shouldn't go back to the sacrificial system to try to atone for their sin. That the perfect and final sacrifice (Jesus on the cross) has been offered, and it would be sin to not trust in that, even damnable sin:
- For [it is] not possible that the blood of bulls and of goats should take away sins. (Hebrews 10:4)
- Above when he said, Sacrifice and offering and burnt offerings and [offering] for sin thou wouldest not, neither hadst pleasure [therein]; which are offered by the law; (Hebrews 10:8)
- And every priest standeth daily ministering and offering oftentimes the same sacrifices, which can never take away sins: But this man, after he had offered one sacrifice for sins for ever, sat down on the right hand of God; From henceforth expecting till his enemies be made his footstool. For by one offering he hath perfected for ever them that are sanctified. (Hebrews 10:11-14)
- Now where remission of these [is, there is] no more offering for sin. (Hebrews 10:18)
- Of how much sorer punishment, suppose ye, shall he be thought worthy, who hath trodden under foot the Son of God, and hath counted the blood of the covenant, wherewith he was sanctified, an unholy thing, and hath done despite unto the Spirit of grace? (Hebrews 10:29)