Jesus Says Blasphemy is The Unpardonable Sin;

But Paul says No.

Paul contends by Jesus "everyone who believes is justified from all things from which you could not be justified by the law of Moses." Acts 13:39.

There is one sin that is unpardonable and thus can not be justified by any atonement under the law of Moses. This is the blasphemy of the name of Yahweh, as specified as unpardonable in Exodus 20:7. The Holy Spirit says in that verse he will not "hold guiltless"  those who insult his name - Yahweh.

In the Greek Septuagint of 257 BC, this was translated that God will "not cleanse" -- where the word "cleanse" was elsewhere used to describe the effect of atonement. Jesus uses the same Greek word to talk about his blood cleansing us. See John ch 15. Hence, there is no justification / atonement ever available for anyone who commits this unpardonable sin as provided under the Law.

Incidentally, before we comment further, the command in Exodus 20:7 speaks of "desolating" words against Yahweh's name -- and thus the English  "takes his name in vain" hardly captures the true meaning in Hebrew. See BibleTools. The same command as Exodus 20:7 is restated in Leviticus 24, but this time uses the word "blasphemy" which means insult -- capturing better in English the true meaning: "And he that blasphemeth the name of Yahweh, he shall surely be put to death" (Leviticus 24:11, 16). (The Greek Septuagint of 257 BC uses "blasphemia" as the translation, and hence is the source of our modern English terminology.)

Jesus in Matthew 12:31 reaffirms this principle in Exodus 20:7 and Leviticus 24: “Therefore I say to you, every sin and blasphemy will be forgiven men, but the blasphemy against the Spirit will not be forgiven men.” This is known as the Unpardonable Sin -- the blasphemy against the Spirit -- a euphemism for God's name of Yahweh. 

Jesus emphasized that any insult on himself can be forgiven, but never be forgiven if on God's name -- with "Holy Spirit" used as a substitution (as was typical when Yahweh's name was spoken but then a scribe did not want to write it
down).  Jesus continued and said: "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." Matthew 12:32.

Jesus said likewise in Mark 3:29: "But he that shall blaspheme against the Holy Ghost hath never forgiveness, but is in danger of eternal damnation."

In each instance, Jesus was clearly referring to Exodus 20:7.

This command against blasphemy is known as the Third Commandment of the Ten. As Dennis Prager, a modern Jewish Rabbi, writes in The Ten Commandments (2015) at pages 20-21: "This is the only one of the Ten Commandments that states that God will not forgive who violates the commandment."  

Hence, Jewish scholars to this day recognize the validity of Jesus' words: blasphemy is the Unpardonable Sin.

In fact, the Bible only says one type of blasphemy (insult) is actually a sin: blasphemy (insult) of Yahweh in Exodus 20:7, as restated in Leviticus 24:11, 16. Any other kind of blasphemy was forgiveable because it was not even a sin. Otherwise, insults (blasphemy) are described as imprudent or unwise: "Whoever belittles his neighbor lacks sense, but a man of understanding remains silent." (Proverbs 11:20.) 

Incidentally, this verse 7 of Exodus 20 about the unpardonable sin is an exception to the principle in the verse just before it. In Exodus 20:6, we read that in all other cases God "shews mercy unto thousands of them that love me, and keep my commandments." (Exodus 20:6.) 

Thus, God's grace extends to everyone who loves him and keeps God's commandments, but grace is never shown to one type of violator under the law given Moses: the blasphemer.  

But what does Paul say about one guilty of the sin of blasphemy? Paul says to the contrary that it is a pardonable sin --- after confessing he once was a blasphemer. Paul wrote: 

Even though I was once a blasphemer and a persecutor and a violent man, I was shown mercy because I acted in ignorance and unbelief.  (1 Tim 1:13 NIV.)

Hence, Jesus calls blasphemy an unpardonable sin in Matthew 12:31, just as is stated in Exodus 20:7. However, to the contrary, Paul says "a blasphemer" was "shown mercy..." -- talking about himself --- an impossibility according to the true Jesus.

Paul in the same vein says:  "And by him all that believe are justified from all things, from which ye could not be justified by the law of Moses." Because blasphemy of the Holy Spirit was the only wrong one could never be justified from under the law given Moses, Paul is again teaching mercy can now be shown to a blasphemer even though Jesus said it was unpardonable.

No wonder that Paulinists insist that despite Jesus calling the sin of blasphemy unpardonable, it is supposedly pardonable now. See Don Wilton's article at Billygraham.org in a 2013. He says:

And, what if you do blaspheme? ... Look into His face and live. He loves you. He died for you. He wants to forgive you. There is hope.Taking the Lord’s name in vain is not the unpardonable sin any more than any of the other Ten Commandments are. This sin can be forgiven because the Lord Jesus Christ came and gave His life.

This is Paulinism! Jesus' words are cancelled. Paul's doctrines are above even the words of Jesus.