Who is wise and understanding among you? From his good conduct show that he works in gentle wisdom. (James 3:13)
The one who is wise from his good (beautiful, honorable, good to look at) conduct (mode of life, how one conducts their life) show (present to light, exhibit, make known) that his works in gentle (meek, kindness, forbearance) wisdom. The essence of a wise person is that they are mature. It is a mature plant that bears fruit. We are a letter, a "poem, created in Christ Jesus prepared in advance to do good good works, so that we walk in them" (Ephesians 2:10)
existing yourselves that our letter, written on our hearts, known and read by all people, knowing because existing Christ's letter, served by us, written not with ink but of the Spirit of the living God, not on tablets of stone but on tablets of fleshly hearts. (2 Corinthians 3:2-3)
Interestingly ποιητής (poiētēs) is translated as the maker of something, and author of a poem; a doer or performer, a performer of the enactments of a law. Now, the Perfect Law is one that matures, not the Mosaic Law, because it did not mature men, neither did serving, tithing... and they do not mature us today.* James speaks of a law that will mature or perfect. Do we have laws in the new covenant? Paul writes of the law of faith, the law of Christ, the law of sin and death, the law that sin is near and sin dwells in our flesh, and the law of the mind...
therefore put aside all moral filthiness, the abundance of wickedness, and receive in meekness the implanted word, that power to save your souls. (James 1:21)
does a source pour forth from the same opening both sweet and bitter?.. can a fig tree produce olives or grapevine figs?... who is wise and understanding among you? (James 3:11-13)
A bridle is put in a horse's mouth so that it may be guided and controlled. If someone can not bridle or control their tongue James writes they are not mature in understanding and wisdom. If someone can't bridle or control the body and gives in to sexual immorality or other desires of the flesh, do they possess wisdom and understanding from God? James writes if anyone lacks wisdom from God ask in faith and God will generously give. A mature person is someone who can bridle or control the body and not give in to its desires.
This is the essence of serving that the great, the mature who have become Christ's letter, become servants of all, to build up others so that they become a poem, Christ's letter to the world. The glory and boasting is given to God. Think about that, your life is a letter, and that letter you present to others is a testimony of the work of Christ in you. If the letter is not yet prepared and you start presenting it to others to read, the fullness of Christ is not read by others. James writes that the way we conduct our lives shows how mature we are and that those who can bridle the body and the tongue show he is the work of gentle wisdom. What does James mean by it is a show of gentle or meek wisdom?
Now, the one looking intently into the maturing law, the law that provides freedom and remains, not a forget hearer rather becoming the poem, he will be blessed in his making. (James 1:25)
"[Christ] is the One we proclaim, to admonish all men, and teach all men in all wisdom so that presenting all men mature in Christ" (Colossians 1:28).
Maturity is the work of ministry.* "The work of ministry is to build up the body into the measure of the stature of the fullness of Christ, into mature adulthood (Ephesians 4:12-13). The devil plants many weeds among the true seed to work against growth in Christ to keep children tossed to and fro in deceitful doctrines, so they will not become mature, of becoming Christ's letter, a poem written to the world. Why does James call it the perfecting or maturing law?
The perfecting is the law that matures and it is the implanted word of God. Jesus said to the Jews who had believed him, “If you abide in my words, you are truly my disciples, and you will know the truth, and the truth will set you free” (John 8:31-32). The words of Jesus provide freedom, and his words James calls the perfecting or maturity law because that is what it does, it brings us into maturity, bearing fruit of being like Jesus. The characteristics of the Holy Spirit are called fruit. John affirms the young person has become strong and overcomes evil as the word of God abides in him (1 John 2:14). So we grow in grace and in the knowledge of Jesus Christ. Wisdom and understanding play a role in this.
do not be deceived my dear brothers, all good gifts and all perfecting gifts exist from above, coming down from the Father of lights with whom no variations of shadows nor shadowy change (James 1:16-18).
To understand what James is saying about these perfecting gifts coming down from heaven we look back several verses. There is a trial, a proving of your faith where endurance is needed as the intended work of endurance is maturity so that you are whole, lacking in nothing (James 1:2-5). If you are not enduring them you lack wisdom from God, so James says ask God who will graciously give his children all things but you must ask in faith (James 1:5-6). The trial here is not brought about by God tempting us with evil, that is not God's nature (though like Job, Peter, and Paul he might let the devil or demons attack us) in himself there is no shadowy change, no acting in the shadowy realm. God doesn't tempt or do evil to bring about good but as James writes we are tempted, by our own fleshly desires, and lured away and enticed. This perfecting gift coming down from God is wisdom with the purpose to mature, to not keep you tossed to and from in deceitful shadowy doctrines, in human craftiness and cunning.
at one time you were not people of God now, presently people of God. Of no mercy, now presently receiving mercy. Dear friends, I urge like as foreigners and exiles to abstain from the desires of the flesh, whatever is against your soul. (1 Peter 2:10-11)
Certainly, as Peter writes fleshy desires wage war against our soul. And as Paul writes evil is near, to use this weakness that sin dwells in our bodies to bring us into captivity to sin in the flesh. So to receive wisdom from God to endure the trial which has the intended work of maturity, power over this temptation, power to put aside all moral filthiness, and abundance of wickedness we need. And to receive we must receive in meekness the implanted word, it is powerful to save our souls (James 1:21). This Peter writes is the goal of faith, the salvation of our souls.
do not be deceived my dear brothers, all good gifts and all perfecting gifts exist from above...
The perfecting law (which is the implanted word of God, who is Jesus) and the perfecting gifts (which as James says is the wisdom of God that we lack to endure the trial) come down from above for the purpose of maturity. We know that the word of God increases our faith (Romans 10:1). That we are strengthened in faith.* And faith without love is nothing so what strengthens is faith energized in love (Galatians 5:6). Agape love is a perfecting love that brings us into maturity (1 John 4:18; Colossians 3:14; 2 John 1:6; John 2:5; 1 John 5:3; John 14:21; John 15:10,14). Thus the love of God is fulfilled when we are brought into the fullness of Christ into mature adulthood, bearing fruit.
Therefore the answer to the question "who is wise and understanding among you?" is the person who is mature. The one from his good conduct shows that he works in gentle wisdom, for it is the one who receives in meekness or gentleness the word of God who is changed by it. And the wise, having learned themselves, understand and know and teach others in gentle wisdom.