Shevuos, Chapter 1, Mishnah 6. The Mishnah now turns to another form of atonement: a person who was tamei and entered the Mikdash deliberately, or who ate sacrificial food deliberately, and did not receive a warning. Had he received a warning he would have received lashes, but here, since he received no warning, he is not lashed. In this case the goat whose service is performed inside, in the Holy of Holies, together with Yom Kippur, is what atones.
And as we saw earlier, this goat fills two roles: it provides temporary protection for someone who had awareness at the outset but has no awareness at the end, until the matter becomes known to him and he brings a korban oleh v'yored - and until that moment the goat shields him; and alongside that, it atones for one who transgressed deliberately and did not receive a warning.
"V'al she'ar aveiros shebaTorah":
The Mishnah goes on to enumerate all the remaining transgressions of the Torah, of every type:
"HaKalos v'hachamuros" - both light transgressions and severe transgressions, as will be detailed below.
"HaZedonos v'hashegagos" - whether he transgressed deliberately or transgressed inadvertently.
"Huda v'lo huda" - this refers to one who inadvertently did an act that carries a doubt of a kareis prohibition. For example, he does not know whether the fat he ate was cheilev, which carries kareis, or permitted fat. "Huda" - the doubt became known to him, and ordinarily he would be obligated to bring an asham talui, but he has not yet brought it and Yom Kippur arrived. "Lo huda" - the doubt only came to his attention after Yom Kippur.
"Asei v'lo saaseh" - positive commandments and negative commandments, and these are what are called the light ones.
"Kerisos u'misos beis din" - transgressions that carry kareis or court-imposed death, and these are what are called the severe ones.
For all of these - "sa'ir hamishtalei'ach mechaper": the goat that was sent out to the wilderness and killed is what atones for all the transgressions listed.
The view of Rabbi Yehudah HaNasi versus the view of the Sages:
It is important to note that the Gemara says our Mishnah follows the view of Rabbi Yehudah HaNasi, who holds that even if the person did not repent, the goat that is sent away atones - for our Mishnah makes no mention at all of any need for repentance.
In practice, however, we rule like the Sages, who hold that the goat that is sent away does not atone for the severe transgressions, those carrying kareis and court-imposed death, except together with repentance. And if he did not repent, it atones only for the light ones, such as positive commandments and negative commandments.
In summary: In this Mishnah we learned that the goat whose service is performed inside, together with Yom Kippur, atones for one who was tamei and entered the Mikdash or ate sacrificial food deliberately without a warning, and alongside that it shields one who had awareness at the outset but not at the end until he brings his korban. For the remaining transgressions of the Torah - the light and the severe, the deliberate and the inadvertent, those that became known and those that did not, positive and negative commandments, those carrying kareis and court-imposed death - the goat that is sent away atones; and in practice, following the Sages, it atones for the severe ones only together with repentance, and without it its atonement extends only to the light ones.