Men Are Especially Known By Their Words (12:31-37).
Having put right the Pharisees' wrong conception about Him He now warns them to beware what they say. For what they say will reveal the truth about them, and they will have to give an account of their very words and what they signify at the Day of Judgment. They will be known by their fruit. ‘You offspring of vipers' indicates that the Pharisees are still directly in mind, compare Matthew 3:7.
The passage continues in a series of contrasts, blasphemy as a whole as contrasted with the blasphemy against the Holy Spirit; speaking a word against the Son of Man in contrast with speaking a word against the Holy Spirit; that such will not be forgiven either in this world/age, or in that which is to come; that the tree and its fruit is either good or is corrupt; that that which is evil cannot speak good things; that a good man brings forth good things, and an evil man brings forth evil things; that by their words men will be justified, or by them will be condemned. In the presence of Jesus men are at a crisis point, and to continually reject His words will be catastrophic (Matthew 12:41-45).
Analysis.
a “Therefore I say to you, Every sin and blasphemy will be forgiven to men, but the blasphemy against the Spirit will not be forgiven” (Matthew 12:31).
b “And whoever will speak a word against the Son of man, it will be forgiven him, but whoever shall speak against the Holy Spirit, it will not be forgiven him, neither in this world, nor in that which is to come” (Matthew 12:32).
c “Either make the tree good, and its fruit good, or make the tree corrupt, and its fruit corrupt, for the tree is known by its fruit” (Matthew 12:33).
d “You offspring of vipers, how can you, being evil, speak good things? For out of the abundance of the heart the mouth speaks” (Matthew 12:34).
c “The good man out of his good treasure brings forth good things, and the evil man out of his evil treasure brings forth evil things” (Matthew 12:35).
b “And I say to you, that every idle word that men shall speak, they will give account of them in the day of judgment” (Matthew 12:36).
a “For by your words you will be justified, and by your words you will be condemned” (Matthew 12:37).
Note that in ‘a' the blasphemy against the Spirit will never be forgiven, and in the parallel men will be condemned by their very words. In ‘b' speaking against the Holy Spirit will not be forgiven either in this world or in that which is to come, while in the parallel men will have to give account for every idle word in the Day of Judgment. In ‘c' the tree is known by its fruit and in the parallel a man is known by the good or evil treasure that comes from his heart. Centrally in ‘d' the Pharisees are shown up as evil by their words.