In the Haftarah this week, we read: "For [up to] three sins of Israel [I can forgive them]." (Amos 2:6)

When a person transgresses one sin, he will be confronted with the test of another sin, so that he become aroused to repent, whereby the first sin will be atoned. When the evil inclination sees this, it tries to overpower the person with this second sin, but [even if he succumbs], G·d defends him, as the verse says, "For three sins of Israel [I can forgive them]."

...G·d does not punish for a person's first two sins.

The Talmud uses this verse as the basis of the statement that G·d does not punish for a person's first two sins. (Yoma 86b, also see Maimonides, Teshuvah 3:5, Keseph Mishneh ad loc) With a third sin though, one has already entrapped oneself within the force of habit, and his repentance then becomes very difficult, as we read in the next paragraph. One is thus held responsible for all successive sins, although they may well be considered being done under the force of compulsion.

However, after a person has already sinned three times, the three levels of his soul - his nefesh, ruach and neshama - are caught up in the kelipot

From here we learn that with every repetition of a physical act, the influence of that act seeps deeper and deeper into one's soul. We also see that someone "caught in the kelipot" - the "shells" or "husks" - does not even realize that he is trapped. Just as shells and husks conceal what is inside them, so do the kelipot prevent one from seeing oneself clearly and objectively.

...the paths of repentance are withheld from him, until G·d has mercy on him.

…and one sin then inevitably brings another in its wake, and the paths of repentance are withheld from him, until G·d has mercy on him.

And this is what the prophet means, "Let us search our paths and analyze them, and return to G·d", (Lam. 3:40) for after one's path has become a trodden way in one's eyes, because "the heart of this people has become thick"; (Is. 6:10) one must search and analyze one's behavior in order to realize that one has sinned.

It is not easy to change a habit, but even more than this, once one has become accustomed to certain behavior, one tends to rationalize it and justify it, thus making it difficult to even admit that the habit needs changing. Only honest soul-searching introspection can see through this self-deception.

Only then will one return to G·d.

[From Keter Shem Tov: translation and commentary by Rabbi Yehoshua Starrett]