Judaism is optimistic about human nature. Judaism believes that human beings have the capacity to change. When Adam and Eve eat the fruit of the Tree of Good and Evil they acquire the ability to discern right from wrong and to make appropriate choices. Free will makes our choices consequential. Judaism is a system of mitzvot (commandments) which govern our relationship to God and to other human beings. We are what we do and we are what we choose, and we are responsible for our choices. Our nature is not predetermined. Therefore a process of assessment and correction is important. This process is known as teshuvah (repentance). Ideally, repentance is not limited to any season or some holy day like Yom Kippur (Day of Atonement). In a very interesting and telling Mishnah Rabbi Eliezer taught, “Repent one day before your death.” (The Ethics of the Fathers 2:10) In the Talmud we find that “his disciples asked him, ‘Does then one know on what day he will die?’ and he replied, ‘Then all the more reason to repent today,’” (B.Shabbat 153a) Judaism teaches us that we should be constantly examining our behavior with the goal of improving ourselves. Obviously this is difficult, and therefore, while it is the ideal, Judaism sets aside a specific period for individuals and the community to engage in an elaborate process of self reflection and teshuvah.
During Elul, the month that precedes Rosh Hashanah (the Jewish New Year) and Yom Kippur (the Day of Atonement), we are supposed to engage in a process of cheshbon hanefesh (an accounting of one’s life) This process is part of the preparation for the formal teshuvah (repentance) which is central to Yom Kippur. And from Rosh Hashanah to Yom Kippur (The Ten Days of Repentance) we should be actively engaged in teshuvah.
Judaism recognizes two categories of mitzvot (commandments), those that regulate our relationship to God (bein adam laMakom), and those that regulate our relationship to other human beings (bein adam lechaveiro), and therefore it recognizes two categories of sin—those committed against God and those committed against other human beings. We are taught that Yom Kippur atones for our sins against God but it does not atone for sins against another human being until the two persons have been reconciled. "The Day of Atonement atones for sins against God, not for sins against man, unless the injured party has been appeased" (Mishna Yoma 8:9). Teshuvah (repentance) is a process which begins with the acknowledgement that a person has sinned, followed by confession, resolve not to repeat the sin, and finally, resisting the temptation to repeat the sin because one has changed through the process of repentance. "What constitutes complete repentance? He who is confronted by the identical situation wherein he previously sinned and it lies within his power to commit the sin again, but he nevertheless does not succumb because he wishes to repent, and not because he is too fearful or weak [to repeat the sin]. How so? If he had relations with a woman forbidden to him and he is subsequently alone with her, still in the throes of his passion for her, and his virility is unabated, and [they are] in the same place where they previously sinned; if he abstains and does not sin, this is a true penitent" (Mishneh Torah, "Laws of Teshuva," 2:1).
Repentance for our sins against other human beings requires an additional step: reconciliation, and sometimes compensation for the wrong we have done. This can be very difficult but is essential to true repentance. In addition, as the person sinned against we are taught to be open to the truly repentant person who comes to us for forgiveness. Leviticus 19:18 teaches us neither to seek vengeance nor to bear a grudge. The willingness to forgive is essential. “It is forbidden for one to be harsh and non-appeasing. One should rather be forgiving and slow to anger, and whenever a sinner asks one for forgiveness one should grant it wholeheartedly." (Mishneh Torah, "Laws of Teshuva," 2:10)
Teshuvah (repentance) is an opportunity to reinvent ourselves. This is a remarkably optimistic and hopeful perspective. The way we live our lives matters. Life is filled with opportunities to change for the better. Our nature is not a given, but created by each of us every moment.
Answered by: Rabbi Peter Knobel