Greetings in Christ from sunny Texas, I am going to insert a short explanation that works for me on the unforgiveable sin i.e. "Blasphemy Against The Holy Spirit"
In Matthew 12, Jesus addresses the "unbelief" of Old Testament Jews in him as the promised "Messiah," and their contributing his miracles of healing to Beelzebub, the prince of devils, rather than the work of the divine Holy Spirit.
Because Christ is not present today performing miracles by the power of the Holy Spirit as in Matt. 12:28, no one today can attribute Christ's power of healing to Beelzebub, the prince of devils, and thereby "blaspheme" against the Holy Spirit.
The sin and blasphemy against the Holy Spirit of Matthew 12:31, was perculiar to and applied only to the "unbelieving" and "blaspheming" Jews of the last generation in Israel before the "end" of the Mosaical age.
Matthew 12 does not address the "unbelief" and condemnation of alien sinners for rejecting the New Testament "gospel" of the Holy Spirit in this New Testament age.
This "unbelief" of the Pharisees in the Messiah and his miracles of healing, and their false charge of contributing Christ's power of healing by the Holy Spirit to Beelzebub, the prince of devils, was the most despicable "blasphemy" against the Holy Spirit possible.
The so-called "unpardonable sin" of today among denominations, a strictly sectarian term and doctrine of denominationalism, is not taught in either the Old or New Testaments.
The "unbelieving" and "blaspheming" Jews of Matthew, Mark, Luke and JohnJ -- before the cross (MMLJBC) -- were the only old covenant people ever able to reject the Messiah under the Old Testament law of Moses -- before the cross, and then reject him when the New Testament age began -- after the cross.
The text and context of Matthew 12 specifically describes the confrontation between Christ, the Jewish Messiah and the "unbelieving" and "blaspheming" Pharisees in Israel.
Matthew 12:1-2 shows the Pharisees accusing Christ's disciples of doing that which is "unlawful" on the sabbath. A clear definition and discussion of Christ, Jews and the Old Testament law of Moses.
Jesus then defends his disciples by illustrating King David's example of eating the shewbread in the temple, or the how priests profaned the sabbath, and all were "blameless" under the law (Matt. 12:3-8).
Immediately, Jesus and his disciples go into a synagogue, and they ask the Messiah if it is lawful for him to heal on "sabbath days" (Matt. 12:9-13).
Matthew 12:14 then states that the "unbelieving" Pharissees "held a council" against Jesus as to how they might "destroy him."
Matthew 12:15-21, Jesus continued to heal "all" in Israel and then quotes and interprets Isaiah 49:6 which prophesied of his work as the Messiah in Israel. That ultimately, although the many Jews in Israel refused to believe in him as the Messiah, when the New Testament age began the Gentile nations would come to trust in him.
Again, in Matthew 12:22-34, the "unbelieving" and "blaspheming" Pharisees and other Jews that accused Christ of healing by the power of Beelzebub, the prince of devils, this was the "blasphemy against the Holy Spirit" of which Christ spake.
Matthew 12:34-38 specifically designates those "unbelieving" and "blaspheming" Jews in Old Testament Israel to whom his teaching was given; those who were accountable to this particular sin against the Holy Spirit. "O generation of vipers...But I say unto you...For by thy words thou shalt be justified, and by thy words thou shalt be condemned...Then certain of the scribes and of the Pharisees answered, saying..."
Christ left no doubt as to who was guilty of the sin of "blasphemy" against the Holy Spirit, and it includes no one in this New Testament age.
While the text and context of the "blasphemy against the Holy Spirit" in Matthew 12:30-31 applied only to the unbelieving and blaspheming Jews in Old Testament Israel, there were other instances and accusations of Jewish "blasphemy" in MMLJ --before the cross -- against things sacred under the law of Moses.
Jesus was falsely accused of "blasphemy" because he forgave the sins of a man sick of palsy.
Matthew 9:3 “And, behold, certain of the scribes said within themselves, This man blasphemeth. (See also Mk. 2:7; Lk. 5:21).
Jesus taught his Jewish disciples that "blasphemies" originated within the heart of man.
Matthew 15:19 “For out of the heart proceed evil thoughts, murders, adulteries, fornications, thefts, false witness, blasphemies