For if we sin willfully after we have received the knowledge of the truth, there remains no more a sacrifice for sins,
Compare on this and following verses, Heb 6:4, &c. There the warning was that if there be not diligence in progressing, a falling off will take place, and apostasy may ensue: here it is, that if there be lukewarmness in Christian communion, apostasy may ensue. if we sin--Greek present participle: if we be found sinning, that is, not isolated acts, but a state of sin [ALFORD].
For if we sin wilfully after that we have received the knowledge of the truth, there remaineth no more sacrifice for sins, (m) Without any cause or occasion, or show of occasion.
26. For if we sin willfully, or voluntarily etc. He shows how severe a vengeance of God awaits all those who fall away from the grace of Christ; for being without that one true salvation, they are now as it were given up to an inevitable destruction.