Mark 3:28-30
28 Verily I say unto you, All sins shall be forgiven unto the sons of men, and blasphemies wherewith soever they shall blaspheme:
29 But he that shall blaspheme against the Holy Ghost hath never forgiveness, but is in danger of eternal damnation:
30 Because they said, He hath an unclean spirit.
The Grace New Testament Commentary - Mark 3:28-30
3:28-30 Jesus already had one clash with the scribes over the issue of forgiveness. Because Jesus had forgiven the paralytic's sins, they accused Him of speaking blasphemies (cf. Mark 2:5-7). The words "Assuredly (lit., "Amen" or "Truly") I say to you" are emphatic and show the solemnity of what He is about to say. This passage is still in the context of the scribes' accusation that Jesus' power is from Satan. Jesus affirms that "all sins will be forgiven and whatever blasphemies they may utter." But the person who "blasphemes against the Holy Spirit never has forgiveness but is subject to eternal condemnation."
The scribes had witnessed the power of Jesus to heal and to cast out demons. Yet they had concluded that He is possessed and empowered by Satan. However, Jesus was anointed by the Holy Spirit (1:10) and had been working in the Spirit's power. This is the immediate context in which Jesus declares the blasphemy against the Holy Spirit.
Furthermore this was not a momentary flash of anger but a settled disposition of their heart. They had consistently refused to hear His words, see His signs, or heed His corrections. Moreover, they sought to influence others by campaigning verbally against Jesus. Possibly these scribes had finalized their view toward Jesus. The concluding statement in v 30, because they said, "He has a demon" may suggest this. However, Jesus never says that these men before Him have blasphemed "against the Holy Spirit." He simply warns them that this is possible.
Many today fear that they have committed the unpardonable sin by blaspheming the Holy Spirit. Such a sensitive spirit is evidence that one's disposition is not "finalized" against Jesus. Though people should honor God's name, an angry outburst directed at God does not fit this context. Also the epistles include no warning against committing such a sin. On the contrary the blood of Christ cleanses from all sin (1 John 1:7, 9). Many believe that this could be committed only by those in this historical context, and cannot be committed today. Regardless, anyone who believes in Jesus has everlasting life and can never perish (John 3:16).
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.
Ruckman Reference Bible - Mark 3:30
3:30 This verse gives you an exact, precise definition of the "unpardonable sin". It has nothing to do with a final rejection of Christ, telling people that a fake healer is filled with the devil, or attributing the work of the Holy Ghost to Satan. It is saying that Jesus Christ has "an unclean spirit". Such a sin could only be committed when Jesus Christ was present, working on this earth.