‘And the tongue is a fire. The world of iniquity (or the article may suggest that we translates as ‘the world of the unrighteous') among our members is the tongue, which defiles the whole body, and sets on fire the wheel of nature (or ‘the course of nature or existence, or of the genealogical sequence'), and is set on fire by hell.'
For following on from the picture of the brushwood and woodland fire lit by a spark, the tongue also is like a fire. It sets things aflame. "A worthless man plots evil, and his speech is like a scorching fire" (Proverbs 16:27). It is almost as though in that tongue lies hidden the sinful world outside the church (the world of iniquity, or of the unrighteous, is the world of greed and covetousness, of boasting and arrogance, of lust and dissension, of backbiting and gossip, and of envy and jealousy), only for it to be brought into the open when the tongue begins to speak, even within the assembly, through careless teachers. And by its words the tongue thus defiles the body of its owner by what it says, both because it reveals that it is sinful and because it arouses its owner to passion and lust and anger and folly as he exercises his tongue foolishly, and it defiles others by doing the same to them, (compare the phrase about the foul nature of malice in James 1:21), and it thus sets on fire the ‘wheel of nature' which is within each one of us and among us all, setting it rolling on its uncontrolled way. And when it does so, let us be in no doubt as to its source. It is set on fire by that very place of destruction that awaits all sinners, and just longs to bring Christians down into it (Gehenna - the place of the lost). That place is, as it were, seeking to bring the lust of the flesh or the mind into the Christian assembly so as to drag it back into the world, and finally into its own clutches.
Or there may be the idea that through the ages the tongue has set on fire men from one generation to another, affecting ‘the continuing wheel of existence' that continues on through history, and that it is still true of our own generation. And if we are not careful such a tongue can even today bring into the assembly by its words the foolish and sinful world outside, ‘the world of the unrighteous', with all its sinful ways. For nothing demonstrates more that our bodies are still subject to that world than our tongues. By them we give ourselves away. (You only have to stop and listen to church members talking to know which world is most important to some of them). And by them we introduce that world to others, when their minds should rather be set on Christ, forcing their minds back to the desirable things of the pleasure ridden world, or offering them what is not good for their souls. It may even be that Christian ‘prophets' were saying such foolish things, and stirring up the feelings and emotions of the whole congregation in the wrong way.
Alternatively what follows in the next verse might be seen as suggesting that the ‘the cycle of existence' (or wheel of nature) refers to the world of nature red in tooth and claw which has to be tamed (as Genesis 1:28 informs us), including all kinds of beasts and birds and creeping things and things in the sea which need to be subdued and dominated (see next verse), thus needing a tamer. But it is rather a world which has been stirred into being untamed by the activities of men within nature as a result of their unruly tongues. This might connect back with the great brushwood and woodland fires (James 3:5), seeing them as caused by advancing armies as so vividly described in the Old Testament (e.g. Isaiah 8:18-19), with their devastating effects on nature as animals driven wild by fear, and totally uncontrolled, make for any haven that they can find. Thus instead of taming them, man by use of his tongue (giving instructions and inciting others to violence), has driven them wild. In the same way men's foolish words can set ablaze the church making them similarly untamed, following the behaviour of untamed and unruly beasts (1Co 11:17-22; 2 Peter 2:1-3; 2 Peter 2:12-22; Revelation 2:20-22).
Or it may refer to the world of sinful man through the ages which alone out of all the round of nature has rebelled against its Creator, and indeed by use of its tongue has regularly set on fire that round of nature, sometimes literally by stirring up war which affects all living things (see James 4:1-2), and more often by stirring up trouble and local dissension. And it does this because it itself has been set on fire by Gehenna.
Or it may refer to ‘the world in its sin' which, stirred up in its ‘round of existence' by foolish tongues, persecutes and harasses the people of God, being drawn in to its harmful activities by foolish things said by the tongues of unwise Christians.
Or the idea may be of the wheel of nature from birth to death with the idea that the tongue affects men through the whole of their lives, introducing them if they are not careful into a world of iniquity and sin.
But whatever way it is the tongue is seen as violently destructive and as being a causer of great distress and harm.
‘The cycle of nature.' This was a concept found in Greek philosophy, but it was the kind of phrase that could easily be taken up and reinterpreted. Christians did not think in terms of a cycle of nature in the sense intended by some Greek philosophers, they believed in time stretching from the beginning to the consummation, and then on for ever. And they would see such a ‘cycle' or ‘wheel' or ‘course' as controlled by God. We can compare how Paul regularly takes up philosophical concepts and gives them a new meaning in the light of the Gospel.