Read all of Matthew 12 carefully

As we all learned in school, context clues go a long way to explaining the meaning of a passage. The same rule applies when reading the Bible. Matthew 12 chronicles an encounter between the Pharisees and Yeshua concerning his willingness to commit actions the halakha of the Pharisees deemed illegal on the sabbath day:

Matthew 12:9 And when he was departed thence, he went into their synagogue:10 And, behold, there was a man which had his hand withered. And they asked him, saying, Is it lawful to heal on the sabbath days? that they might accuse him.11 And he said unto them, What man shall there be among you, that shall have one sheep, and if it fall into a pit on the sabbath day, will he not lay hold on it, and lift it out? 12 How much then is a man better than a sheep? Wherefore it is lawful to do well on the sabbath days.13 Then saith he to the man, Stretch forth thine hand. And he stretched it forth; and it was restored whole, like as the other.14 Then the Pharisees went out, and held a council against him, how they might destroy him. 15 But when Jesus knew it, he withdrew himself from thence: and great multitudes followed him, and he healed them all.

Yeshua embarassed the Pharisees by pointing out that  the Torah clearly states, no one shall bear a burden on the sabbath.  A maimed hand, if it can be healed, qualifies as an unnecessary burden.  Healing wounds would infact serve the sabbath command by removing unneccesary burdens.  He then furthers his point by reminding the Pharisees that in the halakha of the elders a man can get his animal out of a ditch on the sabbath day if its injured or trapped.  By making this point he demonstrated that the Pharisees hold the life and health of Israelites in lower esteem than that of the beasts of burden of Pharisees.  It's no surprise the people in that synagogue left immediately and asked to be healed.

Shortly thereafter, the Pharisee accuse Yeshua of serving the devil and healing with demonic powers. 

Matthew 12:24 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.

Here he points out that he, as a Torah teacher, would make a poor ally for the devil because everything he teaches moves the men as far from the devil as possible.  He then asks what evidence do they bring?  He can heal, but so can the students of the Pharisees.  They created a law unto themselves (the halakha) and now they'll have to play judge one with another ignoring the judgements in the Torah.  However since Yeshua heals fully in accordance with the word of the Torah, that means the kingdom that can only be built by people following the Torah has arrived in Israel.  Also Yeshua says to them "the finger of God" is the method of casting out demons.  The finger of God wrote the Ten Commandments.  Yeshua then puts the nail in the Pharisee's coffin saying:

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.

He has now publicly identified the sect of the Pharisees as invaders into the house of God.  In his eyes, they came to bind and constrain the word of God.  Then they could bind and constrain the people of Israel.  Thereby they steal from the very family of God in his own house.

Now comes the great and frightening realization:

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. 32 And whosoever 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.

Here the Messiah bombards them scriptural references and threats.

To understand the Messiah we need to understand the terms used.  What is the Holy Ghost?  Who is the Son of man?  What is Blasphemy? 

The Holy Spirit

– In Greek Hagia g40 Pneuma g4151 literally “Mouth breath worth protecting"

– In Hebrew Ruach h7307 HaKodesh h6944  literally “Mouth Breath of Separateness"

The oracles of God are the breath breathed into the lips of Moses which Judah was prophesied to protect:

Num 12:8 With him will I speak MOUTH TO MOUTH, even apparently, and not in dark speeches; and the similitude of the LORD shall he behold: wherefore then were ye not afraid to speak against my servant Moses?

YHWH makes it clear in this passage that he breathed his words directly into Moses and if anyone speak against him they will be speaking against the Most High.  Is it any surprise Yeshua, as the living Torah, would be enraged at men who made new laws to accompany the perfect oracles given to Moses?  Yeshua testified of himself saying:

John 6:63 It is the SPIRIT that quickeneth; the flesh profiteth nothing: the WORDS I SPEAK UNTO YOU, they are SPIRIT, and they are LIFE. 

John 12:49 For I have not spoken of myself; but the Father which sent me, he gave me a COMMANDMENT (Torah), what I should say, and what I should speak.

He confirms he only speaks the words YHWH commanded and he speaks spirit and life.  No surprise because the Torah is life. As explained by Solomon:

Proverbs 3:17-18 17Her ways are ways of pleasantness, and all her paths are peace.18 She is a tree of life to them that lay hold upon her: and happy is every one that retaineth her.

Son of Man

Thought Yeshua does refer to himself as the Son of man many times in the New Testament, I believe "Son of man" refers to Ezekial here.  93 times in the Tanak YHWH calls Ezekial "son of man".  No surprise Yeshua would expect them to speak against him, Ezekial prophesied about the elders of Israel saying:

Ezekial 34 1And the word of the Lord came unto me, saying,2 Son of man, prophesy against the shepherds of Israel, prophesy, and say unto them, Thus saith the Lord God unto the shepherds; Woe be to the shepherds of Israel that do feed themselves! should not the shepherds feed the flocks?3 Ye eat the fat, and ye clothe you with the wool, ye kill them that are fed: but ye feed not the flock.4 The diseased have ye not strengthened, neither have ye healed that which was sick, neither have ye bound up that which was broken, neither have ye brought again that which was driven away, neither have ye sought that which was lost; but with force and with cruelty have ye ruled them.5 And they were scattered, because there is no shepherd: and they became meat to all the beasts of the field, when they were scattered.

Blasphemy

We confirmed the meaning of spirit as the Torah, so now we must understand the meaning of blasphemy. This word is blasphemia g988 in the greek which strong's concordance defines as "slander, detraction, speech injurious to another's good name". So how does one detract from or injure the name of the Torah in which God established his good shem? The blasphemer must change it and or atleast reinterpret the words to serve his own modus operandi. Pharisees and Sadducees stand guilty of adding to the word of Moses as they saw fit for the furthering of the traditions of the elder's of Israel.

Tree and Fruit

God called the living Torah a tree (proverbs 3:18) to turn the people of Israel into fruitful trees (Romans 11:15-25).  The fruit of Torah (Galatians 5:22) would show in the works of the believers.  Eventually bringing the kingdom of heaven to the earth.  The pharisees, by adding to the law, created a buffer preventing the fruit of the Torah from blooming in the lives of the believers.  Halakha created a corrupted tree with corrupted fruit as Yeshua points out saying:

Matthew 12:33 Either make the tree good, and his fruit good; or else make the tree corrupt, and his fruit corrupt: for the tree is known by his fruit.

The elders created halakha in the order to keep the people safe from sin, but neglected to remember a simple truth about the thoughts of men:

Matthew 19:17 And he said unto him, Why callest thou me good? there is none good but one, that is, God: but if thou wilt enter into life, keep the commandments.

To close his indictment against them he says:

Matthew 12:34 O generation of vipers, how can ye, being evil, speak good things? for out of the abundance of the heart the mouth speaketh. 35 A good man out of the good treasure of the heart bringeth forth good things: and an evil man out of the evil treasure bringeth forth evil things.

In summery, Yeshua showed the halakha as both the height of hubris and foolishness.  It shows a lack of trust in the Torah and creates new sins YHWH must show his consent for by forgiving them through his system of forgiveness.  This explains why Yeshua said, " blasphemy against the Holy Ghost shall not be forgiven " because God doesn't allow others to define what sin is.  Sin, by definition, is transgression of the Torah (1 John 3:4).