Jewish teachers acknowledged that deliberate sin against God's law ("sin with a high hand" or "defiantly"-see Num 15:30-31; Deut 29:18-20; CD 8.8), such as deliberate blasphemy against God, was normally unforgivable (Jub. 15:34; 1QS 7.15-17, 22-23). Even such a sin as Peter's denial of Jesus (Mt 26:69-75) clearly does not count in the unforgivable category (28:10, 16-20); the context of blaspheming against the Spirit here refers specifically to the sin of the Pharisees, who are on the verge of becoming incapable of repentance. The sign of their hardness of heart is their determination to reject any proof for Jesus' divine mission, to the extent that they even attribute God's attestation of Jesus to the devil.

The equivalent today would be someone who remained so committed to rejecting Christ that she determined to find alternative explanations for any obvious proof (such as miracles) attesting him. Even in what seems to be that case, however, Paul exhorts one of his students and coworkers to remember that we humans cannot judge who has forever crossed that line (1 Tim 1:12-20). Not uncommonly young Christians read about the "unforgivable sin" and fear they have committed it. We therefore must reiterate the point in this context: the sin is unforgivable only because it reflects a heart too hard to repent. Those who desire to repent, troubled by the fear that they may have committed this sin, plainly have not committed it!