James 4:17

‘To him therefore who knows to do good, and does not do it, to him it is sin.'

So there is really only one conclusion that they should come to. They should recognise their mortality and put their efforts into what they know that God wants them to do, and that is to ‘do good'. For if they know what He wants of them and do not do it, for them it is sin.

Thus the stress is on the fact that we should be putting our efforts into doing real good in the world, which is, after all, what we know that we ought to be doing. And for us also, knowing that this is what we ought to do means that it is sin if we do not do it. We should note that the emphasis here, as throughout his letter, is on what we should be doing, not on a negative ‘what we should not do'. For when anyone knows what they ought to do, (such as 1. Avoiding the judgment of others; 2. Being aware of frailty, and therefore looking at things that are unseen rather than having gain as their first concern, because they and it will soon pass away and they will leave it all behind, and especially 3. Doing good wherever possible), and yet does not do it, then that is sin. So he is bringing out that we can sin by what we do, by the attitude that we take up towards life, and by what we do not do, doing genuine good towards others. And it is that that should be our first consideration.

This was one of the stresses of Jesus. The good Samaritan did what was required for a person in need, while the Priest and Levite passed by on the other side (Luke 10:30). The rich man saw Lazarus at his gate and did nothing for him (Luke 16:19). The people brought before Jesus for judgment had failed in their responsibility to do good to His ‘brothers', while those who were accepted had done so (Matthew 25:31). Thus He laid a similar stress on the need for positive goodness, and in the Last Day He will say, ‘inasmuch as you did not do if for the least of these My brothers, you did not do it for Me.'