What is this unpardonable sin?

Matthew 12:31 “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.”

There have been some questions and much debate on this subject for many years. What does this verse really mean? I think one most important question must be answered before I attempt to explain this verse and that is; “can one that is saved ever commit a sin that could never be forgiven?” The answer is without a doubt NO! Anyone who is saved cannot commit any sin that is unforgivable, period. How could God ever tell us that the blood of Jesus Christ cleanses us from ALL sin if there was any sin that was unforgivable? “But if we walk in the light, as he is in the light, we have fellowship one with another, and the blood of Jesus Christ his Son cleanseth us from all sin.” 1 John1:7 The word “all” means – all forms of sin or all matter of sin or sin in whole. Therefore it would be blasphemy against God and an insult to Jesus Christ to declare that there were any sin that was unforgivable for any one who believes in Jesus Christ as their Saviour. John did say in 1 John 5:16 “If any man see his brother sin a sin which is not unto death, he shall ask, and he shall give him life for them that sin not unto death. There is a sin unto death: I do not say that he shall pray for it.” The death spoken of here must be referring to the death of the body because according to Romans 8:35 – 39 nothing can separate us from the love of God that is in Christ Jesus, therefore if there were an “unforgivable sin” or a sin unto spiritual death it would contradict God’s word and therefore we could have no faith in it. Please let us not forget two important facts when reading God’s word, the entire bible is in context and there is no contradiction. However, I must add right here this fact, there is one single sin unto spiritual death and that is the sin of unbelief, the sin of not believing that Jesus Christ is the Saviour of mankind and every single person that is not saved has committed this sin and will spend eternity in hell. John 3:18 “He that believeth on him is not condemned: but he that believeth not is condemned already, because he hath not believed in the name of the only begotten Son of God.” As for our text scripture this is my understanding. The context here is the questioning of whose power that the Lord Jesus Christ was using to perform miracles. We clearly see in verse 24 they told Jesus He cast out these devils by the power of “Beelzebub the prince of the devils.” The name Beelzebub is Chaldee in origin and it means – a dung god or a name of Satan, therefore these folks were telling Jesus He was casting out devils in the name of Satan and not by the power of the Holy Spirit, therefore denying the power of the Holy Spirit. Therefore it was a direct insult to the Holy Spirit. How can one be saved if they refuse to believe in the power of the Holy Spirit? It is also a direct insult against the Holy Spirit to claim that He is not involved in salvation. Beloved we as Christians are saved, we move, and have our being by the power of the Holy Spirit, therefore everything a Christian does that is good and right is done by His power and what a disgrace it is not to give Him His due.