And whosever speaketh a word against the Son of man, it shall be forgiven him: but whosoever speaketh against the Holy Ghost, it shall not be forgiven him, neither in this world, neither in the world to come. Matthew 12:32.
It was just before this that Jesus had a second time performed the miracle of healing a man possessed, blind and dumb, and the Pharisees had reiterated the charge, “He casteth out devils through the prince of the devils” (Matthew 9:34). Christ told them plainly that in attributing the work of the Holy Spirit to Satan, they were cutting themselves off from the fountain of blessing. Those who had spoken against Jesus Himself, not discerning His divine character, might receive forgiveness; for through the Holy Spirit they might be brought to see their error and repent. Whatever the sin, if the soul repents and believes, the guilt is washed away in the blood of Christ; but he who rejects the work of the Holy Spirit is placing himself where repentance and faith cannot come to him.
It is by the Spirit that God works upon the heart; when men willfully reject the Spirit, and declare Him to be from Satan; they cut off the channel by which God can communicate with them. When the Spirit is finally rejected, there is no more that God can do for the soul....
It is not God that blinds the eyes of men or hardens their hearts. He sends them light to correct their errors, and to lead them in safe paths; it is by the rejection of this light that the eyes are blinded and the heart hardened. Often the process is gradual, and almost imperceptible. Light comes to the soul through God’s Word, through His servants, or by the direct agency of His Spirit; but when one ray of light is disregarded, there is a partial benumbing of the spiritual perceptions, and the second revealing of light is less clearly discerned. So the darkness increases, until it is night in the soul. Thus it had been with these Jewish leaders. They were convinced that a divine power attended Christ, but in order to resist the truth, they attributed the work of the Holy Spirit to Satan. In doing this they deliberately chose deception; they yielded themselves to Satan, and henceforth they were controlled by his power.