Num 5:1-4 The LORD spoke to Moses, saying,“Command the people of Israel that they put out of the camp everyone who is leprous or has a discharge and everyone who is unclean through contact with the dead. You shall put out both male and female, putting them outside the camp, that they may not defile their camp, in the midst of which I dwell.” And the people of Israel did so, and put them outside the camp; as the LORD said to Moses, so the people of Israel did.
That Moses was truly a prophet of the LORD. The commands God spoke to Moses were not secret revelations, they were meant to be spread throughout the whole community of Israel. These words of God were authoritative commands, not suggestions. It wasn’t that any of these things made a person or proved them to be a notorious sinner (though that was often wrongly assumed). Rather, it was that leprosy, unclean discharges, and dead bodies were reminders of the effects of sin – from which Israel must separate as they prepared to march towards the Promised Land. We could consider these three sources of uncleanness as an analogy of humanity’s sin nature, inherited from Adam. A leper does not choose leprosy, but inherits it, so our sin nature is not chosen – but inherited from Adam. We choose individual acts of sin, but our sin nature was inherited. At this stage in Israel’s progression to the Promised Land, they had been organized and ordered by God – now, they would be challenged to become a community that valued purity. God desired to make Israel a “Promised Land people” – and that means a purified, holy people. Neither men nor women were to be excluded from this command. Neither perceived sympathy nor perceived superiority could spare someone the effects of sin in the world and our sinful nature. “This does not, of course, mean they were left behind to perish, but that they were not allowed to march in their proper place with the tribes of their people.” God is concerned with far more than our individual acts of sin; He demands our sin nature be addressed. Only in Jesus can our sin nature – (the old man) be crucified, and the nature of Jesus (the new man) be given to us, making us new creations. God does not have a relationship of love and fellowship with the old man, but He does with the new man. (Guzik)
The camps and divisions of priests, Levites, and people being thus settled, now was the time when the law about excluding leprous and unclean persons from the camps was to take place; God having, for wise reasons, appointed that all persons under such legal impurities should, in proportion to the degree of them, be excluded from the community where he himself dwelt by the symbols of his divine presence till they were cleansed again. (Benson)
It is easy to see the effects of sin in another person, but what if our sins were openly exposed and easily recognized by anyone who saw us? What if they were like a flashing spotlight on a billboard seen by anyone near enough to see it. I would think the shame of these known by everyone around us would humble us. They would give us pause before we would criticize others. They would make us aware of the great grace, mercy, and love God has in accepting us as we are. They would surely point us in the direction of what love towards others should be.