In James 3:2 he tells us we all often (G4183; cp. Matthew 9:14) stumble (G4417). In fact, the Scriptures tell us that there isn’t a righteous man in this world who does good who doesn’t stumble (Ecclesiastes 7:20). If there would be a man who never stumbled or erred (G4417) in what he says, that man would be perfect and would be able to control his whole body (James 3:3). The word perfect (G5046) is not meant to be flawless. Rather, it is used to point to a mature man, perfect / mature as in James 1:4 (cp. 1Corinthians 2:6; 14:20; Ephesians 4:13; Philippians 3:15; Colossians 4:12; Hebrews 5:14).
As noted above, the perfect man is able to bridle (G5468) or control his whole person. This word appears in only one other place in the Bible, James 1:26. There, not bridling the tongue breeds self deception; here, James speaks of bridling the whole body (if the tongue is bridled). There, not bridling the tongue leads to vain religion; here, the mature man’s religion is true, because he is in control of what he says and does.
The Scriptures tell us that Noah, Abraham and Job were perfect in their generations (Genesis 6:9; 17:1; Job 1:1). Zacharias and Elizabeth were righteous and blameless before the Lord (Luke 1:6). To be perfect, then, doesn’t mean without flaw or sin. Instead, it refers to a disciplined man or woman who errs much less than someone who doesn’t keep himself in check at all. The apocryphal book of Sirach offers a truism in this regard: “He who can rule his tongue will live without strife; and he who hates babbling will have less evil.” In other words offensive speech breeds strife and an unbridled tongue incurs much trouble in life, which fits in well with James’ context of advising his readers to refrain from being teachers or demanding to be heard in the worship service. Be quick to listen, but slow to speak (cp. James 1:19).
James is drawing upon Jesus’ own words: “…out of the abundance of the heart the mouth speaks” (Matthew 12:34). There, Christ was referring particularly to the scribes and Pharisees who led their whole generation astray:
A good man out of the good treasure of the heart brings forth good things: and an evil man out of the evil treasure brings forth evil things. But I say unto you, That every idle word that men shall speak, they shall give account thereof in the day of judgment. For by your words you will be justified, and by your words you will be condemned. (Matthew 12:35-37)
Yet, even Moses was judged by God for speaking rashly only once, when he was tempted by the people (Psalm 106:33), so the truth of the words: “There is one that slips in his speech, but not from his heart, and who is he that has not offended with his tongue?” (Sirach 19:16), once more fits James’ context of the need to bridle one’s tongue and mature (be perfect) in his walk with Christ.
What a man says reveals his character:
For a good tree doesn’t bring forth corrupt fruit; neither does a corrupt tree bring forth good fruit. For every tree is known by his own fruit. For of thorns men don’t gather figs, nor of a bramble bush do they gather grapes. A good man out of the good treasure of his heart brings forth that which is good; and an evil man out of the evil treasure of his heart brings forth that which is evil: for of the abundance of the heart his mouth speaks. (Luke 6:43-45)
Therefore, what a man says cannot be separated from what he does or in some cases what he doesn’t do. James said “faith without works is dead” (James 2:26), or, put another way, faith that doesn’t cause one to be faithful (James 2:14; cp. Galatians 5:22-23) has no intrinsic value (cp. James 1:26).