what happens to non-Noahide non-Jews after death?

Question

I've heard many Jews and Noahides say that only a non-Jew who follows the Noahide Laws "has a share in the world to come." Yet is this a universal belief in Judaism (ie, do other authorities hold differently), and what does it mean?

Does it mean that one's soul extinguishes permanently upon death? That one experiences permanent gehenna? That one's soul goes to heaven but does not experience the resurrection of the dead? That one's soul must reincarnate again?

The reason I ask is that the standard belief appears cruel, and inconsistent with Hashem's mercy. According to some versions of the belief cited above, if an atheist is a good person and never breaks any of the other Noahide laws (besides the requirement to believe), or if a person follows all the other laws but is a polytheist, he will not experience the afterlife. Isn't this cruel and unjust? It seems Hashem would have mercy and allow non-Jews to have an afterlife consistent with what they deserve based on the preponderance of their deeds, as He does with Jews.

I often hear that unlike Islam and Christianity, Judaism doesn't belief all non-believers go to hell. But this belief is very similar to that.

I note that "has no share in the world to come" phrases are extremely common in rabbinic literature, including the Talmud, and it seems extremely unlikely we are required to believe in them all. For example, Rabbi Akiva said that one who sings Song of Songs in a disrespectful way has no share in the world to come. Yet few people would literally believe one forfeit's one's afterlife for singing a single song the wrong way. Many of these statements sound like they are meant as exaggerated ways of emphasizing the importance of something, rather than a literal statement of cause-and-effect regarding the afterlife. In any case, Rav S.R. Hirsch writes that we need only accept hashkafic statements (other than main tenets of belief) in rabbinic literature, including that Talmud, that accord with our reason and intellect.

Answer 1

In the beginning of cheilek we are told a Jew who believes in techiyas hameisim but does not believe that it is hinted to in the Torah, does not rise from the dead when it happens. Rashi explains who needs him and his beleifs. Meaning, as far as just payback from Hashem goes, you get what you give. The Rambam explains that a good nonbeliever jew gets his reward in this world. Either he or his kids down the line will get paid back for all his and their good that they did, for the sake of goodness. Its only when someone does something on a Godly spiritual level that they get their payback in the Godly spiritual realm. Again, you get what you give. An atheist gets the reward deserving of an atheist, and a believer gets the reward of a believer. This is not crule at all. This is justice on the level expected from the person awaiting that justice.