You're making an exclusive definition that isn't entirely correct.
You claim that "fruit" in Matthew 7 refers
only to false doctrine and the false teachers produced by false prophets. Where does Jesus say that?
Throughout Scripture, "fruit" is repeatedly used to describe a person's conduct, character, and deeds...not just the people they influence.
- Matthew 3:8 – "Bear fruit worthy of repentance." Repentance is demonstrated by a changed life.
- Luke 3:8-14 defines those fruits as generosity, honesty, justice, and contentment.
- Luke 6:43-45 (the parallel passage) immediately connects the tree and its fruit to what comes out of a person's own heart and mouth.
- Romans 6:21-22 speaks of the "fruit" of sinful living versus holiness.
- Galatians 5:19-23 contrasts the works of the flesh with the fruit of the Spirit which both describe behavior and character.
- Ephesians 5:9 speaks of the fruit of goodness, righteousness, and truth.
So the biblical usage of "fruit" is much broader than the narrow definition you're giving to Matthew 7.
Yes, I agree false doctrine is part of a false prophet's fruit. But there's nothing in Matthew 7 that points to it being the
the only fruit Jesus is talking about, specially when the parallel verses point to it being lifestyle.
In fact, the context continues into Matthew 7:21-23, where Jesus condemns those who
practice lawlessness. That fits the broader argument and my point that a tree is recognized by the fruit of its life, not just by the doctrines someone teaches. Specially look at the surrounding teachings too. It's ALL about conduct.