Mark 3:22-30, NKJV
28 "Assuredly, I say to you, all sins will be forgiven the sons of men, and whatever blasphemies they may utter;
29 but he who blasphemes against the Holy Spirit never has forgiveness, but is subject to eternal condemnation" --
Matthew 12:22-32, NKJV
32 Anyone who speaks a word against the Son of Man, it will be forgiven him; but whoever speaks against the Holy Spirit, it will not be forgiven him, either in this age or in the age to come.
That Jesus was working mighty miracles among the people of His day was undeniable. The lame walked, the dumb spoke, the deaf heard, the dead arose and the demon-possessed were set free.The religious scribes and Pharisees who were against Jesus could not ignore or deny the miracles performed by Him, especially those that were done right before their eyes and in front a large crowd of witnesses. So they had two choices: To attribute Jesus'' miraculous powers to the Spirit of God, or to attribute His powers to a demonic spirit. Of course, they did the second.
Jesus told the people that He cast out demons by the Spirit of God or the Holy Spirit (Matthew 12:28). But the scribes said to the people, "He has Beelzebub. By the ruler of the demons He casts out demons." The Pharisees said the same thing: "This fellow does not cast out demons except by Beelzebub, the ruler of the demons." In other words, they credited the wonderful and gracious works of God that were setting oppressed folks free to the most evil being -- Beelzebub, the prince of demons. They rejected the obvious truth before them and perversely twisted it to influence the crowds. By doing this, they were also implying that Jesus was a sorcerer in league with Satan.
That was how hardened and firmly set their hearts were against accepting Jesus as the Messiah. They kept rejecting the Christ despite all the proof given by the Holy Spirit. Their blaspheming against the Holy Spirit was equivalent to rejecting Christ with such finality that no future repentance was possible. This is the unpardonable or unforgivable sin -- permanently rejecting all attempts of the Holy Spirit to draw one to Christ. Pre-cross, the Holy Spirit''s role was to empower Jesus to perform all sorts of miracles (Luke 4:18, Acts 10:38), thereby proving that He is the Messiah. Post-cross, the Holy Spirits role is to confirm the gospel with signs and wonders (Acts 14:3. Romans 15:18-20), as well as to convict the world of sin (John 16:8-9). What sin is that? It is the sin of all sins -- unbelief in the Christ, which only non-believers can be convicted of.
The unpardonable sin is not this idea of speaking generally against the Holy Spirit. For example, some Christians believe that they are on their way to hell because they had a bad thought towards the Holy Spirit or because they had said some unkind words to Him. Then, there are some Charismatic Christians who say that traditional Christians who attribute speaking in tongues, holy laughter or miraculous healings to demons have committed the unpardonable sin. They say that such Christians have spoken against the Holy Spirit and are thus hell-bound. All that is simply not true and it just shows a lack of understanding of what blaspheming against the Holy Spirit really is. Those who believe such nonsense should read the verses again in context.
When the scribes and Pharisees spoke against the Holy Spirit, it was because their hearts were already firmly set against accepting Jesus as the Messiah. Their sin was the permanent rejection of Christ as their Saviour. But when traditional Christians speak unknowingly and unintentionally against the Holy Spirit by attributing tongues, holy laughter and other supernatural manifestations to demons, it simply shows their ignorance of Scripture and even their fear of the supernatural.
They simply do not believe that the gifts of the Holy Spirit are still for today. Most of them are just naive and do not know any better. Therefore, they attribute supernatural manifestations in the church to trickery, psychology, science or demons. But they are certainly not rejecting Jesus as their Saviour. How can they be when they are already Christians? And they are certainly not out to blaspheme against the Holy Spirit. Why would any Christian want to speak against the Spirit of God?