καρπόν

μείνατε ἐν ἐμοι, κἀγω ἐν ὐμῖν. καθῶς τὸ κλῆμα οὐ δύναται καρπὸν φέρειν ἀφ' ἑαυτοῦ ἐὰν μὴ μένῃ ἐν τῇ ἀμπέλῳ, οὕτως οὐδὲ ὑμεῖς ἐὰν μὴ ἐν ἐμοὶ μένητε. — κατὰ Ἰωάννην 15:4

meinate en emoi, kago en hymin. kathos to klema ou dynatai karpon ferein af' heautou ean me mene en te ampelo, houtos oude hymeis ean me en emoi menete. — kata Ioannen 15:4

“Remain in me, and I (will remain) in you. Just as the branch cannot bear fruit from itself if it does not remain in the vine, so neither can you if you do not remain in me.” — John 15:4, translation mine

Unlike God, no man can see into another man's heart. Interpersonal relationships depend on the externalities by which one deduces another's inner character. Some take advantage of this knowledge gap to defraud their fellow man, but Christ gave His disciples advice on how to distinguish true godly character from false:

“Beware of false prophets, who come to you in sheep's clothing but inwardly are ravenous wolves. You will recognize them by their fruits. Are grapes gathered from thornbushes, or figs from thistles? So, every healthy tree bears good fruit, but the diseased tree bears bad fruit. A healthy tree cannot bear bad fruit, nor can a diseased tree bear good fruit.”
Matthew 7:15-18, ESV

Like a tree with its fruit, a life outwardly bears hallmarks of its healthiness. A perverse heart does not open the arms except to glut itself, nor does a malicious spirit extend the hand except to strike another down. Even the most painstaking attempts to disguise a corrupt core fall like limbs from a rotten tree. A sick interior always betrays the death within itself.

In the same fashion, the life of Christ inside those who remain in Him cannot be hidden. Born of and fed by the sap of God's Holy Spirit, the fruit of the Christ follower in turn feeds those who receive it. This fruit is the good works which grow out of the grateful response of the disciple to God's calling to repent and seek Him. These works do not earn God's salvation but proclaim it.

It is with this understanding that Solomon writes, “The fruit of the righteous is a tree of life, and whoever captures souls is wise” (Proverbs 11:30, ESV). Man has lost access to the tree of life since Adam and Eve disobeyed God (Genesis 3:22), and all his striving has not won it back. We are not immortal of our own power. If we bear good fruit, we cannot claim credit. If we gain wisdom in capturing souls to God, we do so in Christ's name. As the vine produces fruit through the branches, so Christ bears fruit through His body of followers. Salvation accordingly comes as God's grace, and our righteousness is Christ in us.

Christ is our tree of life if we remain in Him and drink in His Word. If we fail to remain in Him and instead spurn His teachings, we will bear rotten fruit. God speaks through the prophet Isaiah:

• And now, O inhabitants of Jerusalem
• and men of Judah,
• judge between Me and and My vineyard.
• What more was there to do for my vineyard,
• that I have not done in it?
• When I looked for it to yield grapes,
• why did it yield wild grapes?
• Isaiah 5:3-4, ESV

The answer is that “the backslider in heart will be filled with the fruit of his ways, and a good man will be filled with the fruit of his ways” (Proverbs 14:14, ESV). When God looked to His people who had turned away from Him, He saw the rottenness and bitterness that leached from their hearts into the fruit of their lives.

Although tempting at first bloom, the hollow fruit of wickedness starves and weakens. The ripe fruit of a life in Christ feeds and strengthens to eternal life. Let us not slide back into our former lives of dryness and decay, for “there is a way that seems right to a man, but its end is the way to death” (Proverbs 14:12, ESV).