“…but whoever blasphemes against the Holy Spirit never has forgiveness, but is guilty of an eternal sin”— Mark 3:29 (ESV)
Jesus gave a teaching and a fearsome warning to his enemies. He healed a man who was blind and mute. As he and the crowd were rejoicing, the scribes and Pharisees were seething. They boldly attributed his miracle to Satan.
Jesus, possibly restraining himself, answered the accusation with a teaching: “A house divided against itself cannot stand”. This good deed revealed power over the sinful world and gave the man a new life. It was good (God) vs. evil (Satan). Satan only destroys; the sickness and evil in this world are his attack on God’s work. If Jesus’ work were of the devil, there would be no good result. Any work of the devil that looks good is a facade. Jesus’ miracles proved his power over evil.
However the real answer to their charge was do not say that God’s work is of Satan. The Holy Spirit will not be defamed without consequences. He is warning them, and us, that calling God’s work evil is unforgivable. Be careful how you respond to the work of the Holy Spirit. To disrespect Him might cost your salvation.