Summary: Jesus said we’d know false prophets by their fruit. Do you know what that fruit is?
My sermon to you from these verse may seem at first to be rather dark in focus and content, but the message from our Lord’s own mouth in these verses is a dark one, for those who practice lawlessness.
Let’s read them first, and keep them before our eyes and our minds as we study them.
“Beware of the false prophets, who come to you in sheep’s clothing, but inwardly are ravenous wolves. You will know them by their fruits. Grapes are not gathered from thorn bushes, nor figs from thistles, are they? Even so, every good tree bears good fruit; but the bad tree bears bad fruit. A good tree cannot produce bad fruit, nor can a bad tree produce good fruit. Every tree that does not bear good fruit is cut down and thrown into the fire. So then, you will know them by their fruits. Not everyone who says to Me, ‘Lord, Lord’, will enter the kingdom of heaven; but he who does the will of My Father who is in heaven. Many will say to Me on that day, ‘Lord, Lord, did we not prophesy in Your name, and in Your name cast out demons, and in Your name perform many miracles?’ And then I will declare to them, ‘I never knew you; DEPART FROM ME, YOU WHO PRACTICE LAWLESSNESS’.”
Now just to bring you up to verse 21 and this part of Jesus’ discourse, let me point out a few things from verses 15 through 20.
First, we see that Jesus is warning about false prophets. In that particular setting, He would have been warning them about their religious leaders, who claimed to have the words of God in their mouth, but really had deception and murder and self pride in their hearts. They were phonies; but they were worse than phonies. He called them ‘ravenous wolves’ in sheep’s clothing.
What did He mean by that, and what does it mean for us?
Remember that a false prophet is, by definition, someone who names the name of the Lord, but is not really speaking from the Lord. He is saying “Thus saith the Lord”, when the Lord has not spoken.
There are many Old Testament references that expose false prophets and what God thinks of them. I’ve just selected a few here for emphasis:
“Then the Lord said to me, ’The prophets are prophesying falsehood in My name. I have neither sent them nor commanded them nor spoken to them; they are prophesying to you a false vision, divination, futility and the deception of their own minds.”
Since Jesus says in Matthew 7 (quickview)  that we will know them by their fruits, I want you to pay particular attention in this next passage from Jeremiah, to the life-style of those who are assuming to prophecy in the Lord’s name:
“...because they have acted foolishly in Israel, and have committed adultery with their neighbor’s wives, and have spoken words in My name falsely, which I did not command them; and I am He who knows, and as a witness’, declares the Lord.”
And I’ve chosen just one more verse that expresses the Lord’s opinion of those who are false teachers:
“So My hand will be against the prophets who see false visions and utter lying divinations. They will have no place in the council of My people, nor will they be written down in the register of the house of Israel, nor will they enter the land of Israel, that you may know that I am the Lord God.”