Matthew 12:31-32
31 Wherefore I say unto you, All manner of sin and blasphemy shall be forgiven unto men: but the blasphemy against the Holy Ghost shall not be forgiven unto men.
32 And whosoever speaketh a word against the Son of man, it shall be forgiven him: but whosoever speaketh against the Holy Ghost, it shall not be forgiven him, neither in this world, neither in the world to come.
The Grace New Testament Commentary - Matthew 12:31-32
12:31-32 The Pharisees are in danger of committing (but had not yet committed) the unpardonable sin, which is "blasphemy (insulting language) against" the Spirit's witness to Christ. They are stubbornly denying the Holy Spirit's miraculous witness in the ministry of Christ, ascribing it to Satan instead. Thus they would make their own forgiveness impossible if they continue in this rejection. Such persons will not even begin to understand the identity of Christ as the One who saves. They might speak against Him as "the Son of Man," concluding from His appearance that He is no more than an ordinary human being. But when the Spirit attests His true identity, they are held accountable. When people continue to deny the witness of the Holy Spirit regarding the identity of Jesus Christ and their need for eternal life, the Holy Spirit will eventually cease working on their hearts and minds. Without the convicting and convincing work of the Holy Spirit (cf. John 16:8-11) no person will believe in Jesus for eternal life. Persistent unbelief leads to hardening of the heart that causes the Holy Spirit to give such people over to their unbelief.
The warning Christ gives implies that the Pharisees have not yet committed this sin, but could. Jesus' critics stand at the brink, on the verge of rendering themselves incapable of believing in Jesus for eternal life.
Charles Bing - Grace, Salvation, and Discipleship - The Unforgivable Sin, Matthew 12:31-32 (cf. Mark 3:28-30)
(Salvation) Interpretation: A person can commit this sin that makes salvation impossible, or if he is saved, will cause him to lose his salvation.
Second (Salvation) Interpretation: A person can commit this sin that shows his heart is hardened to the Holy Spirit's convicting work that brings a person to salvation.
It is unfortunate that both unbelievers and believers have lived under the fear of committing this sin and thinking they have been disqualified from salvation. That this is A Truth is clear from whom Jesus is addressing. The audience are the unbelieving Pharisees and scribes who accuse Jesus of an allegiance with Satan (Matt. 12:24-30; Mark 3:22-27). Their verbal accusation prompts Jesus' reply about the sin that cannot be forgiven. Eternal salvation is at issue because this sin can never be forgiven and brings eternal condemnation (Matt. 12:32; Mark 3:29).
Jesus is not speaking of Israel's national rejection of Him, because He says "anyone," which denotes individuals. Also, the warning is about a sin more specific than unbelief in Jesus as Savior. Neither does it seem to be the specific sin of accusing Christ of satanic allegiance, as terrible as that is. Jesus says that blasphemies can be forgiven (Matt. 12:31; Mark 3:28). There is only one blasphemy that cannot be forgiven, and it is not specifically blasphemy against Christ, but against the Holy Spirit. Some interpret this as a sin that can only be committed by unbelievers when Christ is present performing miracles either in His lifetime or in the future kingdom. The issue, however, seems to be the heart attitude more than the time period.
What makes the most sense of this difficult saying is that Jesus speaks of a willful and slanderous rejection of the Holy Spirit's testimony about Christ. This sin is revealed in the perverse verbal accusation that Jesus Christ is in league with the devil. The Father witnesses to the Son both through prophecy and His verbal approval at Christ's baptism. The Son witnesses through His own words and works. These witnesses are external. But the Holy Spirit witnesses through His internal convicting ministry (John 16:7-11). When the Spirit convinces an unbeliever about who Jesus Christ is, and that person nevertheless accuses Him of being satanic, he has committed blasphemy against the Holy Spirit. Matthew's discussion that follows this warning emphasizes how one's words reveal one's heart condition so that "by your words you will be condemned" (Matt. 12:33-37). The accusation that Jesus is of the devil reveals the moral blindness of a person who would call light darkness. It displays a heart hardened beyond hope of forgiveness, because there is nothing left to appeal to the conscience when the Holy Spirit's testimony is rejected and slandered. Any unbeliever who blasphemes the Holy Spirit demonstrates a spiritual condition that precludes a receptive attitude toward the gospel.
According to this interpretation, someone who knowingly and maliciously rejects and slanders the Holy Spirit's convicting ministry about the person of Christ could commit this sin today. It would be hard to know when someone knowingly rejects the Holy Spirit's testimony and is not doing it out of ignorance, but God knows.
If there is a (Discipleship message) present in this warning, it is by implication. If you are a believer, then you have responded positively to the Holy Spirit's testimony about Christ. This should bring assurance that you cannot commit this sin and your salvation is not in jeopardy. If a believer worries about committing this sin, it is a testimony that he is still responding positively to the Holy Spirit's witness. Also, as believers, we have the assurance that God's grace covers every sin (Rom. 5:20; Col. 2:13). As for an unbeliever, if he worries about committing this sin, it is also a testimony that he is prone to respond positively to the Holy Spirit's testimony about Christ. We can say this emphatically: Those who believe in Jesus Christ as Savior are saved and have all their sins forgiven.
Thomas Constable's Expository Notes on the Bible - Matthew 12:31-32
12:31-32 A better interpretation is that blasphemy against the Holy Spirit, in view of the context (vv. 24-28), involved attributing Jesus' works to Satan, rather than to the Holy Spirit. The sin was not a matter of speech; the words spoken simply reflected the attitude of the heart. God would not forgive this sin because the person who committed it in Jesus' day was thereby strongly rejecting Jesus as the Messiah. Even today, the only sin that a person can commit that God will not forgive, and that will result in his or her eternal damnation, is rejection of Jesus Christ (cf. John 3:18). Attributing Jesus' works to Satan was blasphemy of the Spirit in Jesus' day, and this resulted in damnation. Can a person commit this sin today? One can reject Jesus Christ, but one cannot blaspheme the Spirit in the same sense in which Jesus' contemporaries could. To do so, one would have to observe Jesus doing His works and at the same time attribute them to Satan. One could say, therefore, that blasphemy against the Spirit was an unforgivable sin during Jesus' earthly ministry. The unforgivable sin at any time since Jesus began His earthly ministry to the present day is rejection of Jesus Christ.
Ruckman Reference Bible - Matthew 12:31
12:31 Those that worry constantly about this sin (mainly Charismatics and Pentecostals) seldom worry about any other sins. The Fundamentalists spiritualize verses 31-32 to mean "final rejection of Christ", but of course, that is not what the passage says. Evangelist J. Harold Smith had a sermon called "God's Three Deadlines" in which he made it actually "cussing out" the Holy Spirit. In fact, there are atheists on the "Internet" who are trying to get Christian teenagers who are fed up with obeying momma and daddy and going to church to do exactly that. But that ignores the revelation God gave the Apostle John after the Resurrection (see 1 John 1:7). Another way of skirting what God says about the sin is to say that it is attributing the works of the Holy Spirit to the Devil (or vice versa). It has nothing to do with that at all. The Holy Spirit Himself told you clearly what it meant in Mark 3:29-30. It was saying that "He [Jesus Christ] hath an unclean spirit". It was a sin that could only be committed when Christ was here on earth. Many of the Pharisees who rejected Christ in the Gospels later believed on Him in the book of Acts and were saved (Acts 15:5, 6:7).