Our Torah was given to us on at least two occasions. The first revelation just weeks after the exodus was ineffectual as the people built a golden calf a mere 40 days later. The Torah that we have in our possession today was in actuality given after Moshe succeeded in gaining forgiveness for the people, what we today know as Yom Kippur, a day henceforth reserved for renewing our relationship with G-d.
One of the key components of Yom Kippur is vidui, confession in which we acknowledge our many shortcomings and are (hopefully) inspired to try to mend our ways. Interestingly enough the actual mitzvah of vidui does not appear in connection with Yom Kippur but actually appears in this week's parsha, Naso. "G-d spoke to Moses telling him to speak as follows to the Israelites: If a man or woman sins against his fellow man, thus being untrue to G-d and becoming guilty of a crime he must confess the sin that he has committed. He must make restitution for his guilt in full and add unto it the fifth part and give it in respect of whom he hath been guilty (5:5-7).”
While the obligation to confess is mandatory for all sins, our Sages have understood the particular context of this command to be dealing with a case of one who steals from a convert. People are much more prone to harass outsiders and hence the special command here, and in many other places in the Torah, of the special care one must have for converts.
The way our calendar is fixed parshat Naso is always read the week after Shavuot (at least in the Diaspora where our cycle of Torah developed) hinting to the need for collective vidui and teshuva for our sins.
Our Sages teach that before accepting the Torah our ancestors went through a process of conversion. Acceptance of the Torah is almost by definition an act of conversion as we accept upon ourselves the yoke of commandments. It is for this reason that the story of Ruth, the ideal and paradigm model for converts, is read on Shavuot, the day associated with the receiving of the Torah. Confession entails "conversion" as we replace our old ways with new and better ones. The Torah is not only talking about stealing from a "convert" but is rather talking to all of us who in order to properly accept the Torah must undergo our own process of conversion.
Maimonides in his laws of repentance emphasizes that confession must be expressed by the penitent. Thinking it is not enough. Matters of importance are not allowed to be left to the cognitive realm alone. By verbally expressing our regret it makes it easier to be more careful about not repeating one's mistake. In expressing remorse there is a basic difference between sins against G-d and sins against our fellow man (which are also sins against G-d). When we sin against G-d the vidui is not to be publicized but is a matter between man and his Maker. However when one has sinned against his fellow man one must, in the words of the Rambam "confess in public and make known his sin and recount his sin against his friend to others and he tells them 'yes I sinned against so and so and did this and that but today I am repenting and am sorry’.” (Laws of Repentance 2:5)
Most people, even if they acknowledge a wrong they have perpetrated find it very difficult to admit it. Judaism demands this confession. However once a sincere confession is expressed, we must, with some exceptions, accept the apology and move forward without the issue ever coming up again. Let us learn how to confess and how to accept the teshuva of others.