1 And Yahweh spake unto Moses and Aaron, saying,
2 When a man shall have in the skin of his flesh a rising, a scab, or bright spot, and it be in the skin of his flesh like the plague of leprosy; then he shall be brought unto Aaron the priest, or unto one of his sons the priests:
Leprosy and running issues are...
the subject of priestly recognition and of sacrificial purification when mere diseases (such as fevers, agues, distempers, choleraic affections, etc.) are passed over without note or provision ...the treatment of leprosy was spiritual rather than hygienic in its object; while, like all the physical appointments of the law of Moses, it was of good hygienic tendency...
Law of Moses Ch 27
3 And the priest shall look on the plague in the skin of the flesh: and when the hair in the plague is turned white, and the plague in sight be deeper than the skin of his flesh, it is a plague of leprosy: and the priest shall look on him, and pronounce him unclean.
In general, those forms of leprosy that were "in sight deeper than the skin", and affected the colour of the hair, were bad cases. Those that were apparently in the skin only, were to be shut up for seven days, to see how they got on; and if, at the end of seven days the plague spot was no larger, the case was one for cure and healing.
The great test of uncleanness was the spreading or not spreading--the affecting or not affecting of other parts.
Law of Moses Ch 27
34 And in the seventh day the priest shall look on the scall: and, behold, if the scall be not spread in the skin, nor be in sight deeper than the skin; then the priest shall pronounce him clean: and he shall wash his clothes, and be clean.
Pronounced clean - typifying repentance and reconciliation.
though burdened with what Paul calls "sin that dwelleth in me", they were not servants of sin but the servants of righteousness--sinners forgiven--lepers healed.
... 'wickedness is only fatal when persisted in: that
"if the wicked forsake his way, and the unrighteous man his thoughts, and return unto the Lord, he will have mercy upon him; and to our God, for he will abundantly pardon" (Isa. 55:7);
and that if the wicked will
"turn from all the sins that he hath committed, and keep all my statutes, and do that which is lawful and right, he shall surely live; he shall not die. All his transgressions that he hath committed, they shall not be mentioned unto him" (Ezek. 18:21-22).
Law of Moses Ch 27
46 All the days wherein the plague shall be in him he shall be defiled; he is unclean: he shall dwell alone; without the camp shall his habitation be.
"He is unclean," said the Law. That is, his malady technically put him in the category of those not in Covenant with God. Upon his cure, therefore, he had first to be reinstated as a full member of the Covenant People. The Law devised a special ritual ordinance to make this possible. First the priest (a type of God here, of course) examined him outside the Camp, and confirming that his plague was really healed, gave authority for the ritual to be followed which would enable him to be pronounced clean, i.e., once more in Covenant with God as he had been before he fell victim to the plague.
"Then shall the priest command to take for him that is to be cleansed two birds alive and clean, and cedar, and scarlet, and hyssop" (Lev. 14: 1-4).
Law and Grace Ch 9
There were professors of the truth in Peter's day, of whom he says they "cannot cease from sin", "their conscience is seared as with a hot iron", This is a different class. These were the incurable lepers who were apostolically directed to be dealt with as the Mosaic type prescribes. Moses says, "Put them out of the camp", Paul says,
" Put away from among yourselves that wicked person" "Know ye not that a little leaven leaveneth the whole lump?" "Keep no company with any man called a brother who is a fornicator, a covetous man, an idolater, or a railer, or a drunkard, or an extortioner."
But doubtless the final fulfilment of the type will not be seen till it is proclaimed concerning the New Jerusalem:
"There shall in no wise enter into it anything that defileth, neither whatsoever worketh abomination or maketh a lie; but they which are written in the Lamb's book of life" (Rev. 21:27).