NOTES for Lev 13:29-59
The connection between illness, even serious illness, and defilement is not visible at first glance. In fact, one can imagine a sin that defiles a person, but illness? A person is not guilty of his illness. One could, of course, say that every illness is a consequence of sin, but hardly anyone will dare to assert that this exact, concrete sin committed by a person produced this exact illness from which he is now suffering. There are, of course, cases in which the connection is more or less obvious, but they are far fewer than cases that do not allow an unambiguous interpretation.
Besides, a reasonable question arises: why leprosy in particular? There are many other diseases in the world, widespread enough, especially in those times, that killed just as effectively as leprosy, and sometimes much more quickly. Meanwhile, the answer to the question lies in the understanding of defilement that was characteristic of the pre-Christian era and was also reflected in the Book of Leviticus.
A person was defiled not only by the consequences of a sin he had committed, although by them first of all, of course. A person was defiled by everything connected in one way or another with death, with the world of shadows, with Sheol. In those times death was all-powerful. In the fallen world it was absolute; everything ended with it, and life was only an episode, bright, encouraging, inspiring, but only an episode.
Even those paths that could lead a person beyond death and its power did not change the picture: after all, one could get away from death only by getting away from life as well, at least from the life by which this world lived. Only after the coming of Christ did the situation change radically: now death has over us exactly as much power as we allow it to have. Before, however, everything was different, and diseases like leprosy separated a person from life, and therefore from God, from God's presence, from God's holiness. Death is incompatible with God's life and with God's holiness.
It is impossible to be sanctified while dying. Today, as we complete our earthly path, we remain in the space of God's holiness, in the Kingdom, if, of course, we have shared in its life. Before the coming of Christ, however, death meant departure from God's world. And leprosy was not life; it was slow death. Life in dying, sometimes prolonged for decades. Such a life in dying could not be sanctified, and that is why lepers were unclean. This is exactly why the Gospel says so much about Jesus healing lepers: so that we may understand how the Kingdom differs from this world.