Leviticus 13:20

In the first case the boil is healed, but in its place there may be a white swelling or a reddish-white bright spot. This is too serious to pass over. It must be brought to the priest. The boil did not prove leprosy, but it could give leprosy, hidden until now, the chance to show itself. And that is reason enough to call the priest to look: in God's eyes, indifference is as intolerable as meddling with what He has not authorised.

If two symptoms showed up — the hair in the sore turned white, and the sore deeper than the skin — then no question remained. It was leprosy, and the priest was to declare the person unclean. The white hair speaks of the decay of spiritual strength. The sore deeper than the skin shows that the sin is not just a small lapse... But when the case is clear, then God's word is clear: the person must be pronounced unclean.

First, the hair turned white is the sign of strength leaving... Freshness and vigour are gone. There may seem to be as much activity as before, but it takes more effort. There may even be more life on the outside, while inside it is weakened and fading.

Then the spot looks "deeper than the skin." This needs much closer attention than the white hair... It is simple enough to say that it means what is not on the surface. But how do we know that in the case of the sin we have to judge? No doubt this is designed to put us to work and to make us feel our need of God... "If any of you lacks wisdom, let him ask God, who gives generously to all without reproach, and it will be given him." (James 1:5)

So there was this important provision: a man is not made the judge of his own sin. The law required the Israelite to bring his condition to someone else for inspection, and that someone else pictures a spiritual man, because that is what a priest means. He is one who has the right of access to God. So he should have his senses trained to tell good from evil by the standard of the sanctuary. He must not be swept along by conventional opinions, or by traditional thoughts, or by what people call public opinion.

There is a difference between personal weakness and the active energy of evil — between simple faults and blemishes in the outward character, and sin at work in us... Take an irritable temper as an example. I should judge it in myself; I should make allowance for it in another. Like "the burning boil" in the case of an Israelite, it may become the source of real defilement — the ground for being shut out of the assembly. Every form of weakness must be watched, in case it becomes an occasion of sin.

There are real differences here, as the New Testament also teaches us. "Anyone caught in any transgression" (Gal. 6:1) is not the same as the serious case of someone who has made a habit of being sexually immoral, greedy, an idolater, a reviler, a drunkard or a swindler (1 Cor. 5:11). In the first case the person needs other believers to restore him. In the second case he must be put out from the fellowship of the saints — though the goal is his recovery in the end.