This statement (Matt 12:32, par Mk. 3:29, Luke 12:10) has been the subject of much questioning. Obviously the reference here is not to the naming of the Holy Spirit in a blasphemous utterance, for in Matt. 12:32 even blasphemy against the Son of man can be forgiven. Among the many attempts at exegesis, the most convincing is the suggestion that the man who blasphemes against the Holy Spirit is he who has recognized that God is working through the Holy Spirit in the actions of Jesus, and who quite consciously "misrepresent faith in God as faith in the devil.  This saying is an extremely serious warning against the demonic and scarcely conceivable potential in man: To declare war on God.  This is not done in weakness and doubt, but by one who has been overcome by the Holy Spirit and who knows very well on whom he is declaring war" (E. Schweizer, The Good News according to Mark, 1971, 87; cf. H.W. Beyer, TDNT I:624; O.E. Evans, "The Unforgivable Sin", ExpT 68, 1956-57, 240-44). This is the blasphemer who does it deliberately, after encounter with the God of grace, as the context shows. For Jesus has just been accused of casting out demons by Beelzebul, the prince of demons. "Therefore he who blasphemes the Spirit is no longer speaking against a God who is distant, about whom he entertains mere foolish thoughts, but against the one who makes evident to him his gracious work, and confirms it with his manifest, divine seal. He is a man who ought to give thanks, not to blaspheme" (A. Schlatter, on Matt. 12:32).

W.L. Lane draws attention to Sifre on Deut. 32:38 (end): "The Holy One, blessed be he, pardons everything else, but on profanation of the Name [i.e. blasphemy] he takes vengeance immediately" (The Gospel of Mark, NLC, 1974, 145) Lane goes on to comment: "This is the danger to which the scribes exposed themselves when they attributed to the agency of Satan the redemption brought by Jesus. The expulsion of demons was a sign of the intrusion of the Kingdom of God. Yet the scribal accusations against Jesus amount to a denial of the power and greatness of the Spirit of God. By assigning the action of Jesus to a demonic origin the scribes betray a perversion of spirit which, in defiance of the truth, chooses to call light darkness. In this historical context, blasphemy against the Holy Spirit denotes the conscious and deliberate rejection of the saving power and grace of God released through Jesus' work and act" (ibid). Thus blasphemy here is much more serious than the taking of the divine name in vain which a believer may have done before coming to repentance and faith.

It may be said to those who have been tormented by fear that they have committed the unforgivable sin that their concern is itself a sign that they have not committed the sin envisaged in Jesus' teaching here. Lane's interpretation also helps to explain the distinction drawn between blasphemy against the Son of man and blasphemy against the Holy Spirit. The distinction suggests that "while an attack on Jesus' own person, as son of Man and therefore 'hidden', is pardonable, any speaking against the power by which he works (i.e. the divine endowment for his messianic ministry) will not be pardoned" (D. Hill, The Gospel of Matthew, New Century Bible, 1972, 318). For such an action would be deliberately to attribute to Satan the action of God himself. (NIDNTT, v. 3, pp. 343-344)

What is blasphemy against the Holy Spirit? Though many suggestions have been offered, I think the answer lies in the context here (Luke 12:7-12) and in the context of redemptive history. Remember that the Holy Spirit had not yet been poured out, and it is the Spirit who causes men to recognize who Jesus is. Hebrews 6 and 10 contain discussions of unforgivable sins, but the distinction between blasphemy against Christ and the Spirit has disappeared. Jesus seemed to be saying this: Because the Holy spirit has not yet been poured out in fullness, the Jews will be forgiven for blaspheming the Son of Man. They will be given a second chance to repent, as we see in the book of Acts. If, however, they continue to blaspheme after the Spirit has come, they will not be forgiven. But what is the sin, specifically? Since it is blasphemy, we must see it essentially as a verbal sin. In context it is the sin of saying that Jesus Christ is of the devil. Jesus was willing to excuse this blasphemy before Pentecost; but, in the new covenant era it is not longer excusable. If a person curses Jesus, but does not really know who Jesus is, that sin is forgivable. But if the Holy Spirit has borne witness to a person that Jesus is indeed the Son of God, and that person curses Him, it cannot be forgiven.