(Serm. 71, 12, 21) Or else impenitence itself is the blasphemy against the Holy Ghost which hath no remission. For either in his thought or by his tongue, he speaks a word against the Holy Ghost the forgiver of sins, who treasures up for himself an impenitent heart. But he subjoins, Because they said, He hath an unclean spirit, that he might show that His reason for saying it, was their declaring that He cast out a devil by Beelzebub, not because there is a blasphemy, which cannot be remitted since even this might be remitted through a right repentance: but the cause why this sentence was put forth by the Lord, after mentioning the unclean spirit, (who as our Lord shows was divided against himself,) was, that the Holy Ghost even makes those whom He brings together undivided, by His remitting those sins, which divided them from Himself, which gift of remission is resisted by no one, but him who has the hardness of an impenitent heart. For in another place, the Jews said of the Lord, that He had a devil, (John 7:20.) without however His saying any thing there about the blasphemy against the Spirit; and the reason is, that they did not there cast in His teeth the unclean spirit, in such a way, that that spirit could by their own words be shown to be divided against Himself, as Beelzebub was here shown to be, by their saying, that it might be he who cast out devilso.
(in Marc. i. 17) The Lord has also bound the strong man, that is, the devil: which means, He has restrained him from seducing the elect, and entering into his house, the world; He has spoiled his house, and his goods, that is men, because He has snatched them from the snares of the devil, and has united them to His Church. Or, He has spoiled his house, because the four parts of the world, over which the old enemy had sway, He has distributed to the Apostles and their successors, that they may convert the people to the way of life. But the Lord shows that they committed a great sin, in crying out that that which they knew to be of God, was of the devil, when He subjoins, Verily I say unto you, All sins are forgiven, &c. All sins and blasphemies are not indeed remitted to all men, but to those who have gone through a repentance in this life sufficient for their sins; thus neither is Novatusm right, who denied that any pardon should be granted to penitents, who had lapsed in time of martyrdom; nor Origen, who asserts that after the general judgment, after the revolution of ages, all sinners will receive pardon for their sins, which error the following words of the Lord condemn, when He adds, But he that shall blaspheme against the Holy Ghost, &c.
(ubi sup.) Neither however are those, who do not believe the Holy Spirit to be God, guilty of an unpardonable blasphemy, because they were persuaded to do this by human ignorance, not by devilish malice.
The meaning of the example is this: The devil is the strong man; his goods are the men into whom he is received; unless therefore a man first conquers the devil, how can he deprive him of his goods, that is, of the men whom he has possessed? So also I who spoil his goods, that is, free men from suffering by his possession, first spoil the devils and vanquish them, and am their enemy. How then can ye say that I have Beelzebub, and that being the friend of the devils, I cast them out?
We must however understand, that they will not obtain pardon unless they repent. But since it was at the flesh of Christ that they were offended, even though they did not repent, some excuse was allowed them, and they obtained some remission.
Or this is meant; that he will not deserve to work out repentance, so as to be accepted, who, understanding who Christ was, declared that He was the prince of the devils.
(Vict. Ant. e Cat. in Marc.) The blasphemy of the Scribes having been detailed, our Lord shows that what they said was impossible, confirming His proof by an example. Wherefore it says, And having called them together unto him, he said unto them in parables. How can Satan cast out Satan? As if He had said, A kingdom divided against itself by civil war must be desolated, which is exemplified both in a house and in a city. Wherefore also if Satan's kingdom be divided against itself, so that Satan expels Satan from men, the desolation of the kingdom of the devils is at hand. But their kingdom consists in keeping men under their dominion. If therefore they are driven away from men, it amounts to nothing less than the dissolution of their kingdom. But if they still hold their power over men, it is manifest that the kingdom of evil is still standing, and Satan is not divided against himself.
(Vict. Ant. e Cat. in Marc.) He says indeed, that blasphemy concerning Himself was pardonable, because He then seemed to be a man despised and of the most lowly birth, but, that contumely against God has no remission. Now blasphemy against the Holy Ghost is against God, for the operation of the Holy Ghost is the kingdom of God; and for this reason, He says, that blasphemy against the Holy Ghost cannot be remitted. Instead, however, of what is here added, But will be in danger of eternal damnation, another Evangelist says, Neither in this world, nor in the world to come. By which is understood, the judgment which is according to the law, and that which is to come. For the law orders one who blasphemes God to be slain, and in the judgment of the second law he has no remission. nHowever, he who is baptized is taken out of this world; but the Jews were ignorant of the remission which takes place in baptism. He therefore who refers to the devil miracles, and the casting out of devils which belong to the Holy Ghost alone, has no room left him for remission of his blasphemy. Neither does it appear that such a blasphemy as this is remitted, since it is against the Holy Ghost. Wherefore he adds, explaining it, Because they said, He hath an unclean spirit.
(non occ.) And because He has already shown by an example that a devil cannot cast out a devil, He shows how he can be expelled, saying, No man can enter into a strong man's house, &c.
Because they were saying, "He has an unclean spirit." For those who neither believe in the Holy Spirit nor believe He is God, nor believe He is indeed God but less than the Father and the Son, and confess this, being led by human ignorance rather than devilish envy, are held by the crime of unforgivable blasphemy: specifically those Jewish leaders and others corrupted by a similar pestilence of envy, blaspheming against majesty, will perish without end. However, what is said according to Matthew, that whoever blasphemes against the Holy Spirit, or speaks a word against the Holy Spirit, will not have forgiveness either in this age or in the future, is given to be understood that some faults are forgiven in this age, while others in the future. For what is denied about one fault, the consequent understanding is clear because it is granted about some. Nevertheless, it should be believed that this can happen with small and minor sins, such as continual idle talk, immoderate laughter, or the sin of concern for familial matters, which is rarely conducted without fault even by those who know how to avoid blame, or in not serious faults by the error of ignorance, all of which still weigh after death if not forgiven while still in this life. However, it should be known that no one will obtain any purification for even the smallest sins unless, while still in this life, they merit to obtain it through good deeds.
And because He has already shewnby an example that a devil cannot cast out a devil, He shows how he can be expelled, saying, “No man can enter into a strong man’s house”
[AD 430] Augustine of Hippo on Mark 3:23-30