Matthew 12:31 “Therefore I say to you, any sin and blasphemy shall be forgiven people, but blasphemy against the Spirit shall not be forgiven."
"Unpardonable" is attributing the things of God to be of satan. We know this clearly because of the context of the scripture surrounding that passage. In verses 22-28, Jesus had just healed a demon-possessed, blind and mute man, the crowds being amazed actually said,
“This man cannot be the Son of David, can he?” (v.23)Such talk has no reception amongst a proud 'know-it-all' Pharisee... after all, only THEY would recognize any 'Christ' first!
"But when the Pharisees heard this, they said, “This man casts out demons only by Beelzebul the ruler of the demons.” (v.24)Some have feared that speaking the Lord's name in vain is such a sin, but in the context of the Word, we see that it's clearly rejecting the very heart of God. Further on, Jesus teaches that,
“Either make the tree good and its fruit good, or make the tree bad and its fruit bad; for the tree is known by its fruit." (v. 33)Now there is a difference between just not understanding, or a burst of frustration and it thoughtlessly comes out and leads to an 'I'm sorry, Lord', repentance vs. actually knowing that it bears good fruit and aligns with the Word of God and the person commits the unpardonable by damning these good things because of pride in a wrong doctrine…and that's what it essentially is…. people doing just what they did to Jesus who hurt their 'pride' and so they decided to vilify and kill Him instead of test and consider. God can do nothing with a proud heart and it was satan's big crime…and so that's what this 'unpardonable' sin is really about.
God wants our hearts... He doesn't want lip-service... and He'll use the weakest or even strangest of circumstances to test if we really will check the fruit. You've heard, "study to show thyself an approved workman...", well the ultimate test is "do we recognize Him"? You can bet He's watching OUR fruit!