James 3

The following passages are from the NIV and commentary from Calvin and Douma.

1Not many of you should presume to be teachers, my brothers, because you know that we who teach will be judged more strictly. 2We all stumble in many ways. If anyone is never at fault in what he says, he is a perfect man, able to keep his whole body in check. 3When we put bits into the mouths of horses to make them obey us, we can turn the whole animal. 4Or take ships as an example. Although they are so large and are driven by strong winds, they are steered by a very small rudder wherever the pilot wants to go. 5Likewise the tongue is a small part of the body, but it makes great boasts. Consider what a great forest is set on fire by a small spark.
James explains the evils which proceeds from the neglect of restraining the tongue, in order that we might know that the tongue can do MUCH good or MUCH evil. James notes that if it is modest and well regulated, it becomes a bridle to the whole life, but that if it is loose and violent, like a fire it destroys all things. And he represents it as a small or little fire, to intimate that the smallness of the tongue will not hinder the power it has to extend far and wide to do harm.

6The tongue also is a fire, a world of evil among the parts of the body. It corrupts the whole person, sets the whole course of his life on fire, and is itself set on fire by hell.
The tongue is set afire by hell itself. There dwells the father of lies, the Devil. Jesus spoke this against the Jews who were boasting that Abraham was their father. He pointed out that they did not understand the truth, so they were not free sons of Abraham, but slaves of sin. “You are of your father the devil, and the desires of your father you want to do.” Jesus’ criticism is revealing, not only for the Jews of His day, but for all of us. Lying lives very deep within us, because we have been defiled with lying by the father of lies. Through his fall into sin, man has not simply been defiled with the lie, but dominated by it. The truth of God is exchanged for the lie, so that the creature is worshiped instead of the Creator. The lie is not an incidental phenomenon, but is characteristic of fallen man. All men became deceitful (Rom. 3:9-18)

7All kinds of animals, birds, reptiles and creatures of the sea are being tamed and have been tamed by man, 8but no man can tame the tongue. It is a restless evil, full of deadly poison.
This is a confirmation of the last verse; that Satan rules most effectively by the tongue. And he proves that it cannot be brought to due order by making comparisons. For he says that there is no animal so savage or fierce, which is not tamed by the skill of man, -- that fishes, which in a manner inhabit another world, -- that birds, which are so quick and roaming -- and that serpents, which are so detrimental to mankind, are sometimes tamed. Since then the tongue cannot be restrained, there must be some secret fire of hell hidden in it. If we desire to structure our life aright, we must especially strive to restrain the tongue, for no part of man does more harm.

9With the tongue we praise our Lord and Father, and with it we curse men, who have been made in God's likeness. 10Out of the same mouth come praise and cursing. My brothers, this should not be. 11Can both fresh water and salt water flow from the same spring? 12My brothers, can a fig tree bear olives, or a grapevine bear figs? Neither can a salt spring produce fresh water.
He uses the comparisons in this verse in order to show that a cursing tongue is something monstrous, contrary to all nature, and subverts the order everywhere established by God. When you think of some of these things – a spring yielding both salt and fresh water – it seems so absurd to us! It is a chaotic mixture that goes completely against the natural order. We should be turned off just as much by the double tongue as we are by such a fountain.

13Who is wise and understanding among you? Let him show it by his good life, by deeds done in the humility that comes from wisdom.
The Lord teaches his people to be meek and to be courteous to others. They, then, are alone wise in the sight of God, who connect this meekness with an honest conversation; for those that are harsh and stubborn, though they may excel others in many virtues, do not yet follow the right way of wisdom.

14But if you harbor bitter envy and selfish ambition in your hearts, do not boast about it or deny the truth.
That we may then really glory that we are the children of God, he bids us to act calmly and meekly towards our brethren; otherwise he declares that we are lying in assuming the Christian name.

15Such "wisdom" does not come down from heaven but is earthly, unspiritual, of the devil. 16For where you have envy and selfish ambition, there you find disorder and every evil practice.
Men, following their own sense, or minds, or feelings, soon became a prey to the delusions of Satan. James meant to express something heavy, even that the malignant and the slanderer does everything confusedly and rashly, as though he were beside himself; and therefore he adds, every evil work.

17But the wisdom that comes from heaven is first of all pure; then peace-loving, considerate, submissive, full of mercy and good fruit, impartial and sincere.
He now mentions the effects of wisdom from above which is completely contrary to the former effects. He says first that it is pure; which excludes hypocrisy and ambition. He, in the second place, calls it peaceable, to intimate that it is not contentious. In the third place, he calls it kind or humane, that we may know that it is far away from that immoderate austerity which tolerates nothing in our brethren. He also calls it gentle or polite; by which he means that it widely differs from pride and malignity. In the last place, he says that it is full of mercy, etc., while hypocrisy is inhuman and relentless. By good fruits he generally refers to all those duties that benevolent men perform towards their brethren; as though he had said, it is full of benevolence.

18Peacemakers who sow in peace raise a harvest of righteousness.
He therefore adds, by those who make peace; which ought to be explained: they who STUDY peace, are nevertheless careful to sow righteousness; nor are they slothful or negligent in promoting and encouraging good works; but they moderate their zeal with the condiment of peace, while hypocrites throw all things into confusion by a blind and furious violence.