If a person wants to be forgiven on Yom Kippur, does he first have to do teshuvah? This question is the subject of a disagreement in the Gemara. Rebbi (the compiler of the Mishna) holds that even if one does not do teshuvah, the essence of the day of Yom Kippur - the mere fact that the day has passed - grants atonement.
However, the Chachomim (Sages) say that Yom Kippur atones only for those who do teshuvah. The Halachah follows the view of the Chachomim.
The Rebbe explains that everyone agrees that the atonement of Yom Kippur is brought about by the holiness of the day; it is only that to attain that holiness one is required to do teshuvah.
The Alter Rebbe points out that kaparah (atonement) means 'scrubbing', scrubbing off the dirt of sins. The day of Yom Kippur not only cancels punishment, but also removes any 'stains' or 'dirt.' For on this day the inner bond between the essence of a Jew and the essence of Ha-shem is revealed, and hence any super-ficial 'stains' are automatically nullified.
Definitely Forgiven
One year, at the end of Yom Kippur, the tzaddik Rebbe Levi Yitzchak of Ber-ditchev announced, "it is well known that whenever a person is in doubt as to whether a blessing is required, he should refrain from reciting it. It is therefore clear that since we recite the blessing stating that Hashem forgives our sins, this is surely so, without any doubt whatever."
At the end of Yom Kippur, the custom in every Lubavitcher shul is to sing a march of simcha and victory, to express our certainty that we have been completely forgiven. When this niggun was sung at 770, the Rebbe's face would shine. From atop his chair he would dance and encourage the singing with tremendous joy.
Good Yom Tov!
The night after Yom Kippur is so much a Yom Tov that on that evening we wish each other a "Good Yom Tov!" It is therefore a mitzvah to eat and rejoice at this time, when a Heavenly voice announces to the Jews to "go and eat with joy."
The Rebbes made a point of washing for a full meal, even though they were no doubt exhausted from their strenuous service throughout the day. At the table they would sing niggunim and share words of Torah.
The Rebbe related: once on the morning following Yom Kippur, the Jews in a small town got up early to daven shacharit and found a Polisher chassid dancing around the amud (prayer stand) singing Anim Zemirot, displaying his yearning to Hashem. They realized that he had been so lost in his singing and dancing that he had danced all night, completely forgetting that he was still fasting.
It is the custom to begin preparations for the sukkah on the evening directly after Yom Kippur, at least in conversation. The Rebbe explains that since this is the time when kelipot (negative spiritual forces) are being returned to power, one protects himself by engaging in matters of the sukkah, which are a protection like the clouds of glory.
reprinted from The Weekly Farbrengen by Merkaz Anash, on-line at The Weekly Farbrengen.com