Rabbi Rubin pointed out an apparent contradiction within Rambam. On the one hand, in 1:3, Rambam stresses that one can do teshuva for any sins. On the other hand, in chapters 3 and 4, Rambam lists various sins for which one apparently cannot do teshuva. The specific example Rabbi Rubin gave as an example was "poresh min hatzibbur."
It is possible that we need to make a distinction between teshuva (return) and kapparah (atonement) in the Rambam.
Although Hashem accepts the teshuva of anyone at any time, kapparah is effected only under certain circumstances. Rambam states in 1:3 that "teshuva mechaperet al kol ha'aveirot" and then goes on to describe four different scenarios in 1:4 - immediate kapparah, and three other cases where teshuva is "toleh" (probationary) and kapparah occurs after some other event, such as Yom Kippur, yisurin, or death, in the most stringent instances.
In chapter 3, from 3:6 and on, Rambam details what types of sins disqualify an individual from having a portion in the world to come, and in 3:14, Rambam qualifies the entire discussion to individuals who do not do teshuva before they die.
In chapter 4, Rambam lists a number of aveirot that prevent teshuva, not kaparah. Rambam’s lashon is “ain Hakadosh Baruch Hu maspik beyado la’asot teshuva,” in other words, the individual does not get an opportunity. Rambam then goes on to discuss these aveirot in detail. Again, the whole discussion is qualified at the end of the perek by saying that teshuva is not impossible in the cases.
I see Rambam’s view of teshuva as a partnership between man (and woman) and Hashem. Man is responsible for teshuva, Hashem is responsible for kaparah. Hashem designed human nature such that mitzvah gorreret mitzvah and aveira gorreret aveira – that one tends to engage in habitual behavior. When an individual engages in the sins described in chapter 3 and 4, the individual sets up a habitual behavior that is very hard to break – Hashem is not responsible for the behavior, as this effect is probably a side effect of having free will. It is exceedingly difficult, but not impossible, to break out of the behaviors Rambam describes because all of them deny that Hashem exists.
This is similar to the idea behind the age-old question about Hashem hardening Pharaoh’s heart, and how the language used starts out saying that Pharaoh hardened his own heart and then changes to Hashem doing it to Pharaoh. In essence, Hashem “did it” because this is how He set up human nature, not that Hashem did anything special to Pharaoh. Pharaoh did it to himself.
This is entirely consistent with the statement that Hashem never gives up on anyone; people only give up on themselves. Ultimately, according to Rambam, it appears that people give up on themselves when they fail to recognize that Hashem exists and that He never gives up on them. If they truly believed in Hashem, then they would not give up on themselves, inasmuch as Hashem never does. People who do not believe in Hashem, by definition do not believe in teshuva or kaparah (why should they?) and thus, do not have an opportunity to engage in teshuva as the process has no value and is of no interest to them.
Questions for discussion:
- Is there any relationship between the use of the term K-V-D when Moshe tells Hashem in Shemot 4:10 that he is a "k'vad peh u'k'vad lashon," its use in places such as "vayachbed Pharaoh et libo" in Shemot 8:28, and its use as an adjective when describing some of the plagues, such as "kaved meod" in Shemot 9:18?
- What is the difference between the verb CH-Z-K and K-V-D? Sometimes CH-Z-K is used (the sense of intensifying or making stronger) such as in Shemot 9:35, in other places K-V-D (the sense of making heavier or more massive) such as in Shemot 8:28.
- Comments on the Rambam chapter 5 and on are appreciated, as some of the material there is very challenging.

