Matthew 12:33
In today's lesson, Jesus begins by rebuking the Pharisees, something HE does a lot. This time it's over their inability to distinguish between that which is good, and that which is truly evil. Most of the study relates around the statement Jesus makes in the middle of the study on how we can whether someone is really following HIM or not. The proof is in their fruit. A good tree bears good fruit, a bad tree bears bad fruit.
We do not have to cut open the trunk of an apple tree to figure out whether it is an apple tree or not. We just need to taste its fruit. Someone who is following Jesus, while still a sinner, will still stumble and fall from time to time, but we will still bear the fruit of repentance, and faith in Jesus. These words, such as the words the Pharisees had uttered, and such as our confession of faith in Jesus as our Savior and Lord, matter; they reveal what is really going on inside our hearts.