This is a tough passage on multiple levels. Jesus draws a line in the sand in verse 30. Then he addresses the unforgivable sin in verse 31-32. He says that we will all be known by our fruit in verses 33-35. Finally, he reveals that our words will either justify or condemn us in verses 36-37. There is a lot of serious issues to think about here. More on that later this week.
Matthew 12:30-37 (ESV)
30 Whoever is not with me is against me, and whoever does not gather with me scatters. 31 Therefore I tell you, every sin and blasphemy will be forgiven people, but the blasphemy against the Spirit will not be forgiven. 32 And whoever speaks a word against the Son of Man will be forgiven, but whoever speaks against the Holy Spirit will not be forgiven, either in this age or in the age to come.
33 “Either make the tree good and its fruit good, or make the tree bad and its fruit bad, for the tree is known by its fruit. 34 You brood of vipers! How can you speak good, when you are evil? For out of the abundance of the heart the mouth speaks. 35 The good person out of his good treasure brings forth good, and the evil person out of his evil treasure brings forth evil. 36 I tell you, on the day of judgment people will give account for every careless word they speak, 37 for by your words you will be justified, and by your words you will be condemned.”