Someone once came to me in tears, almost shaking, saying, "I'm convinced that I have offended the Holy Spirit, and committed the unpardonable sin!" I put my arm around them and said, "It's pretty evident that you haven't committed the blasphemy of the Holy Spirit -- because you're still concerned about it. The fact that your heart isn't hardened, that it even bothers you, proves that you haven't!"
A misunderstanding of Matthew 12:31-32 has caused a lot of heartache to Christians. This is where Jesus said, "Therefore I say to you, every sin and blasphemy will be forgiven men, but the blasphemy against the Spirit will not be forgiven men. 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."
The Pharisees to whom Jesus was speaking were revealing a condition of the heart. They had just seen Jesus heal a man who was blind and mute -- an obvious miracle, done by the power of the Holy Spirit -- and yet they attributed it to Satan (Matthew 12:24). That indicated a willful, obstinate hardness of heart for which they felt no conviction at all. The work of the Holy Spirit is to point people to Jesus Christ. For someone who's been resisting that work to take this evidence and be able to say "That's from Satan," indicates their heart is desperately hard ... perhaps at the point of no return.
In Ephesians 4:18-19, Paul refers to a group of people "having their understanding darkened ... because of the blindness of their heart ... being past feeling ... " And he wrote about those who had "their own conscience seared with a hot iron" (1 Timothy 4:2).
Billy Graham explained it this way: "The unpardonable sin is rejecting the truth about Jesus Christ. It is rejecting completely and finally the witness of the Holy Spirit which declares Jesus is the Son of God, Who alone can save us from sin."
Why is that unpardonable? Hebrews 2:3 tells us, "How shall we escape if we neglect so great a salvation?" If we keep resisting and fighting, eventually we can push Christ away so long that we feel no conviction. The Spirit of God isn't striving with us at all anymore. That's the worst condition a person could ever get to! If we hear truth and we get clever at deflecting it -- saying "maybe later" -- we can become so hardened, so calloused, that we don't feel any longer.
There comes a time when God turns out the lights, when any further chance for salvation is finally lost. That's why we are told, "Now is the accepted time; behold, now is the day of salvation" (2 Corinthians 6:2).
When you hear the Holy Spirit saying, "Change now," do it while your heart is tender. Don't become one of those "clever" ones who deflect truth, who experience no life, no real spark anymore. If you are one who has heard the gospel and rejected it up till now: While there is light, while there is feeling, respond!