NOTES for Lev 6:1-30
Cleansing from the consequences of a committed sin is impossible without God's participation; this was obvious to every Yahwist in every age. Yet the cleansing of a person is a divine-human process, and the person participates in it together with God. The issue is repentance for sin, without which no cleansing is possible. Repentance is a practical thing; regrets and bitter tears alone are not enough. The penitent is called first of all, insofar as possible, to compensate his neighbor for the harm caused by his sin.
Sin, of course, is terrible not only because it affects one's neighbors; it is terrible first of all for the sinner himself, because sin puts a wall between him and God. It is precisely this wall that God's action on a person during the purification sacrifice helps to break down. The person is called to enter into the process of his own cleansing and actively participate in it. Cleansing comes down first of all to eliminating the consequences that sin produces in a person's life. Returning what was stolen, what was found and hidden, what was taken unlawfully, is one element of such elimination of consequences.
The issue here is not only compensating the injured parties for the damage, even many times over. The issue is to stop being a thief, and that is not the same thing as simply refraining from theft. One must become a different person, one for whom theft is impossible because it is incompatible with his inner state. God can help a person change in this way, but only if the person in turn helps Him. Restitution many times over in such a context is not simply payment for the trouble, for the moral harm inflicted in addition to the material harm.
What matters here is the very readiness to give back more than one took. This is not punishment; it is training, the training of the habit of giving without counting how much one has taken oneself. If you took less, give more, and then, if such a practice becomes a custom, at a certain moment the thought of theft will simply disappear from consciousness once and for all. It will begin to seem absurd and completely unacceptable. Of course, there are no guarantees here; everything depends on the specific person. Yet the possibility of becoming another person with God's help does exist, and who will use it and how is another question.