"And the scribes who came down from Jerusalem said, 'He has Beelzebub,' and, 'by the ruler of demons He casts out demons.' So He called them to Himself and said to them in parables: 'How Can Satan cast out Satan? If a kingdom is divided against itself, that kingdom cannot stand. And if a house is divided against itself, that house cannot stand. And if Satan has risen up against himself, and is divided, he cannot stand, but has an end. No one can enter a strong man's house and plunder his goods unless he first binds the strong man. And then he will plunder his house. Assuredly, I say to you, all sins will be forgiven the sons of men, and whatever blasphemies they may utter; but he who blasphemes AGAINST the Holy Spirit never HAS forgiveness, but is subject to eternal condemnation' - because they said, 'He has an unclean spirit.' "(Mark 3:22-30)
Why would those who blaspheme against the Holy Spirit be unforgiven, yet any other sin or blasphemy be eligible for forgiveness? Because the new and living way that Jesus Christ brought to Israel, and now to all men, cannot be "had" without learning to be led by the Holy Spirit. Look at the context in which the scribes made their blasphemy against the Holy Spirit: He was preaching/teaching the kingdom, healing the sick, providing sustaining miracles, making little much with some left over, and casting out demons which left those who had been overcome in a right state of mind. All that ministry could not be considered anything but good. Yet, I am impressed that "greater things than these (these healings, deliverances) you also will do, because I go to the Father" was on His mind. We cannot become like Him without the indwelling and the empowerment of the Holy Spirit. As the Word of God informs us, 'to walk just as He walked'.
"There is therefore now no condemnation to those who are in Christ Jesus, who do not walk according to the flesh, but according to the Spirit. For the law of the Spirit of life in Christ Jesus has made me free from the law of sin and death."(Romans 8:1,2)
We are made a new creation, speak with other tongues, understand what we are called to in Him and become complete all by the Spirit of Christ Jesus. You see then that mankind never "has" forgiveness, walking with Jesus Christ as He walked and manifesting His Father's ways, if they blaspheme AGAINST the Holy Spirit.
"Then He said to them, 'Take heed what you hear. With the same measure you use, it will be measured to you; and to you who hear, more will be given. For whoever HAS, to him more will be given; but whoever DOES NOT HAVE, even what he has will be taken away from him." (Mark 4:24,25)