What does it mean to judge a tree by its fruits?

This is in response to Bruce Charlton’s post, “The problem of Mormonism (for mainstream Christians)” at Junior Ganymede, and is adapted from my comment thereto. The “problem” Bruce discusses is how non-Mormon Christians can account for Mormons as a group bearing “good fruit”, while adhering to what they consider to be false doctrine. Bruce’s opinion apparently is that Mormons bear good fruit because of their doctrine; whereas non-Mormon Christians believe the good fruits come in spite of their doctrine, or have no relation to it.

But my focus is on the scriptural passages underlying the discussion, mainly Mt. 7:15ff.

The post and some of the comments seem to be proceeding on the assumption that Jesus intends “fruits” as a criterion for judging the truth or falsity of a religion. If so, then obviously it can’t mean that there will be entirely good fruits and no bad fruits whatsoever; under that criterion, no religion on earth could qualify. It’s also doubtful whether it’s a relative standard, as in, that religion with more good fruits than any other must be the true[est] one.

However, Jesus doesn’t say that you should judge a prophet by the fruits of the doctrine he preaches. Rather, he says that “you will recognize them” – false prophets – “by their fruits”. He continues, “Not everyone who says to me ‘Lord, Lord, did we not prophesy in your name, and cast out demons in your name, and do many mighty works in your name?’” Now, prophesying and casting out demons and doing mighty works are good fruits, are they not? At least the casting out of demons, surely. And yet Jesus may still say to such people, “I never knew you.” Why? Beause they worked lawlessness: “And then will I declare to them, ‘I never knew you; depart from me, you workers of lawlessness.’”

So, being a “worker of lawlessness” seems to be what he means by bearing bad fruit. Other translations are “you evildoers”, “ye that work iniquity” and “you lawbreakers”. The word for “lawlessness” is anomia, defined by Strong’s as “illegality, i.e. violation of law or (genitive case) wickedness:—iniquity, × transgress(-ion of) the law, unrighteousness”.

Another place where a tree failing to bear good fruit is cut down and thrown into the fire, is in Mt. 3:

“But when [John the Baptist] saw many of the Pharisees and Sadducees coming to his baptism, he said to them, “You brood of vipers! Who warned you to flee from the wrath to come? Bear fruit in keeping with repentance. And do not presume to say to yourselves, ‘We have Abraham as our father,’ for I tell you, God is able from these stones to raise up children for Abraham. Even now the axe is laid to the root of the trees. Every tree therefore that does not bear good fruit is cut down and thrown into the fire.”

Here again it doesn’t appear that doctrine is the issue, because it’s individual Pharisees and Sadducees who are being condemned, based on their failing to “bear fruit in keeping with repentance”. So it seems to me that what is being said is, “Don’t follow people whose lives don’t bear fruit in keeping with repentance”, or, “Don’t follow people who transgress the laws of righteousness”.

In Mt. 12:33-37, Jesus seems to be equating good and bad fruits with the words that people speak, as when he says “How can you speak good, when you are evil?” — a clear parallel with the statement, “a bad tree can’t bear good fruit”. “For out of the abundance of the heart the mouth speaks. The good person out of his good treasure brings forth good, and the evil person out of his evil treasure brings forth evil.” And we will be judged by this “fruit”:  “I tell you, on the day of judgment people will give account for every careless word they speak, for by your words you will be justified, and by your words you will be condemned.”

And in many other places the New Testament scriptures speak of bearing the fruits of righteousness unto salvation. This is always in the context of individual exhortations to forsake sin and do good. For example, Romans 6:19ff:

“[J]ust as you once presented your members as slaves to impurity and to lawlessness leading to more lawlessness, so now present your members as slaves to righteousness leading to sanctification. For when you were slaves of sin, you were free in regard to righteousness. But what fruit were you getting at that time from the things of which you are now ashamed? For the end of those things is death. But now that you have been set free from sin and have become slaves of God, the fruit you get leads to sanctification and its end, eternal life.”

So it seems to me that Jesus is saying that a prophet should be judged by his personal righteousness: Is he living a sinful life? If so then he is a false prophet, for he is a worker of lawlessness.

As far as I can see, the New Testament doesn’t discuss testing the truth or falsity of doctrine in terms of whether it bears good or bad fruit. Probably because doctrine is simply true or false, and not all doctrine bears directly on behavior. Also because people are perfectly capable of receiving good doctrine and yet still bearing bad fruit or no fruit, as in the Parable of the Sower (Mt. 13:3-23).