Next follows that troublesome statement, where Christ teaches that although God will willingly forgive all manner of sin and blasphemy, yet there is the one exception which can never have forgiveness: blasphemy against the Holy Ghost.  There are numerous ideas about what this unspeakably horrible sin is, but I incline presently towards an interpretation which seems most fair to the context.  Going back to verse 22, where Christ cast out the devil, eliciting the hateful response from the Pharisees, we find the key to understanding this difficult notion.  The Lord Jesus had cast out the evil spirit, we find in verse 28, through the power of the Spirit of God, Who dwelt in Him without measure.  But the Pharisees had asserted that His work was done through the power of Satan.  Was not this an act of blasphemy?  To impute the work of the divine Spirit to Satan is certainly blasphemous, and this seems to be the sin which Christ has in mind.  Viewed this way, I understand Christ to be saying that the sin which can never be forgiven in this world or in that to come, is imputing the work of the Spirit of God to Satan. 

This ought to make us very careful in ascertaining whether a work is of God before we impute it to the work of any spirit, good or bad.  I would also say, for the comfort of those who may be troubled with fear that they have committed the unpardonable sin, that if their conscience is still alive towards God, and they have desires to repent and serve Christ, then there can be no doubt that they have not committed that sin which alienates them from God forever.