The "speaking" or blaspheming against the Holy Ghost is the sign of a very rancorous and very violent dislike in the heart against Him; and it is not the word taken abstractedly, but that evil and determinate state of heart which that word proves which constitutes the "sin against the Holy Ghost."
I. We have in the Bible four separate sins against the Holy Ghost laid out in a certain order and progression. (1) First, there is the grieving of the Holy Ghost. This occurs when you allow something in your heart and life which impedes and weakens the Spirit's inward work. (2) Next, in the downward course, comes resisting the Holy Ghost. And that is when, with great resolution, you set yourself positively to act contrary to the known and declared will and precepts of the Spirit. (3) From this it is an easy step to quench Him; when, being vexed and annoyed at influences which restrain you, or by voices which condemn you within, you endeavour to put it out, as water on fire, stifling it that it may die overlaying the work of God within you, in order that you may escape. (4) There is a fourth stage, when the mind, through a long course of sin, proceeds to such a violent dislike and abhorrence of the Spirit of God that all infidel thoughts and horrid imaginations come into the mind. The man obstructs and withstands the kingdom of Christ everywhere; and that is the unpardonable sin.
II. The misery and horror of that state lies in this, that it is a state that cannot repent. It cannot make one move towards God. The Spirit is gone. There is no pardon now, because there can be no desire for pardon. There is and there can be in that man no gleam of spiritual thought, because the Author and Giver of it is gone for ever.
J. Vaughan, Fifty Sermons,2nd series, p. 359.
I. Observe, Christ speaks of Himself here as the Son of man,the Son of God in a disguise, as it were; God under the veil of human flesh. Can we wonder that He should look with a merciful and forgiving eye upon any of His brethren who, not suspecting His greatness, should rudely jostle against Him in the crowd? Suppose, for instance, a king were to assume for purposes of state the disguise of a subject, and to mingle with the simplest and rudest of his people, and suppose that while in such disguise he were to meet with an insult; would not a broad line of demarcation be drawn between an insult so offered and an act of avowed treason against the king upon his throne? A comparison of this kind will be of considerable help to us in understanding our subject. Even the murderers of Christ sinned against the Son of man, against Christ in His human nature; whereas, had they known who it was whom they crucified, many might possibly have been overwhelmed with shame and have besought His forgiveness.
II. But in the case of blasphemy against the Holy Ghost no such plea can be set up. Here we have a sin not against God in the guise of Jesus the son of Joseph the carpenter, but against God in His essential Deity, God upon the throne of heaven, God who does good and is the Author of all good both in heaven and earth. The sin of the Jews which our Lord rebuked partook of this character; for they had said that He was under the influence of, and in league with, an unclean spirit; to do good, to love mercy, and to perform acts which undeniably tended to overturn the kingdom of Satan and establish the kingdom of God this, they said, was the work of the devil. Now unquestionably this was to put darkness for light and light for darkness, to confound all distinctions between good and evil, to confuse the works of Satan and those of the Most High God, as though they were not the exact opposites of each other. The person who does fully commit this sin places himself exactly in the position of the lost angels; the sin of Satan is that of deliberately worshipping evil and hating good, and on this account is unpardonable sin unpardonable for this reason, if for no other, that it cannot be repented of.
Bishop Harvey Goodwin, Parish Sermons,3rd series, p. 350.
References: Matthew 12:31; Matthew 12:32. P. J. Gloag, Homiletic Quarterly,vol. iii., p. 206; H. W. Beecher, Sermons,3rd series, p. 352; S. Cox, Expositor,2nd series, vol. iii., p. 321; R. Scott, University Sermons,p. 64; J. C. Hare, The Victory of Faith,p. 288.