Every kind of sin and blasphemy can be forgiven for people, but blasphemy against the Holy Spirit will not be forgiven.
Luke 12:10
And whosoever shall speak a word against the Son of man, it shall be forgiven him: but unto him that blasphemeth against the Holy Ghost it shall not be forgiven.
Matthew 12:24-31
24 But when the Pharisees heard it, they said, This fellow doth not cast out devils, but by Beelzebub the prince of the devils.25 And Jesus knew their thoughts, and said unto them, Every kingdom divided against itself is brought to desolation; and every city or house divided against itself shall not stand:26 And if Satan cast out Satan, he is divided against himself; how shall then his kingdom stand?27 And if I by Beelzebub cast out devils, by whom do your children cast them out? therefore they shall be your judges.28 But if I cast out devils by the Spirit of God, then the kingdom of God is come unto you.29 Or else how can one enter into a strong man’s house, and spoil his goods, except he first bind the strong man? and then he will spoil his house.30 He that is not with me is against me; and he that gathereth not with me scattereth abroad.31 Wherefore I say unto you, All manner of sin and blasphemy shall be forgiven unto men: but the blasphemy against the Holy Ghost shall not be forgiven unto men.
Blasphemy involves speaking disrespectfully about sacred entities, and thus, blaspheming against the Holy Spirit is equating its works with those of the devil. This act is mentioned in the Bible, including Saul, who later became the Apostle Paul. Paul expressed that he was shown mercy for his blasphemy because it was committed in ignorance and unbelief. Hence, the blasphemy against the Holy Spirit, which Jesus cautioned against, must involve a deliberate and knowledgeable denouncement of the Holy Spirit.
1 Timothy 1:13
Who was before a blasphemer, and a persecutor, and injurious: but I obtained mercy, because I did it ignorantly in unbelief.
Individuals may fall from grace by committing acts such as blasphemy against the Holy Spirit or apostasy. Such actions are generally associated with those who have a mature understanding of their faith. Conversely, hasty statements made against the Holy Spirit out of ignorance or disbelief may be forgiven if the speaker is unaware of the gravity of their words.
Hebrews 6:4-6
4 For it is impossible for those who were once enlightened, and have tasted of the heavenly gift, and were made partakers of the Holy Ghost,5 And have tasted the good word of God, and the powers of the world to come,6 If they shall fall away, to renew them again unto repentance; seeing they crucify to themselves the Son of God afresh, and put him to an open shame.
From a human standpoint, it’s difficult to determine when someone becomes accountable for blasphemy and commits the unforgivable sin. We can trust that God knows everyone’s heart and will judge fairly on this matter. Nonetheless, the Scriptures indicate that when a person becomes a “reprobate,” they are devoid of conviction from God.
Romans 1:28
And even as they did not like to retain God in their knowledge, God gave them over to a reprobate mind, to do those things which are not convenient
Thus, if someone feels convicted and repentant for possibly having blasphemed the Holy Spirit, they have not reached the point of it being unforgivable, or else they would be indifferent. Maintain a heart that is tender and receptive to Him. Hear His voice as it speaks to you through His Word today.