The Gemara in 12b says that one gets atonement for his sins for feeling embarrassed at his sin (or according to some commentaries that specific sin). How can one get atonement just for feeling embarrassed - doesn't one need all the stages including vidui and kabala lehaba?
Yehonasan Gefen, Ramat Beit Shemesh
1. The Me'iri writes that the shame that a person feels for his sins is the basis of feeling regret over them, and in turn regret is the basis of Teshuvah. It appears that the Me'iri's intent is to explain that if the sinner starts by being embarrassed, he will inevitable reach all the different essential parts of Teshuvah in the course of time.
2. The Meromei Sadeh (of the Netziv of Volzhin) proves from the Gemara in Sanhedrin (104a) that embarrassment alone is not sufficient. The Gemara there states that the reason why the evik king Achaz is not mentioned as one of the kings who had no share in Olam ha'Ba is that he had "Boshes Panim" -- he was embarrassed in front of Yeshayah ha'Navi. Nevertheless, the Gemara here does not cite Achaz as proof that embarrassment atones for all of one's sins, because even though Achaz merited Olam ha'Ba because of his Boshes Panim, there is no proof that it sufficed to attain complete atonement for him. The Neziv writes that the difference between Achaz and Shaul ha'Melech, who was forgiven entirely as the Gemara here explains, was that Achaz still remained a rebel against Hash-m, even though he was personally embarrassed in front of Yeshayah. In contrast, Shaul not only was embarrassed at what he had already done, but he also decided never to do it again. According to the Netziv, it is clear that one indeed needs the entire parts of Teshuvah, such as Kabalah le'Asid, to attain complete atonement.
3. The Ben Yehoyada (DH Kol ha'Oseh) writes that when a person is embarrassed he blushes, and this is comparable to death, in the same way that the Gemara in Bava Metzia (59a) states that one who publicly embarrasses his fellow man is considered as though he spilled blood. Since embarrassment is equivalent to death, the principle stated by the Mishnah in Yoma (85b) -- that death and Yom Kippur atone together with Teshuvah -- may be applied. However, clearly Teshuvah -- with Viduy, Charatah, and Azivas ha'Chet -- is required together with the embarrassment. The Chidush of the Gemara here concerns those very severe crimes that the Gemara in Yoma (86a) states cannot be atoned for before death. If the sinner is embarrassed, this is eqivalent to death, and he will receive atonement if the other necessary components of Teshuvah are present.
Kol Tuv,
Dovid Bloom