[Formendacil]

If I may interject with my interpolation, I do not think Bêthberry was so much concerned with the particular sins of Sodom and Gomorrah, and how that was applicable to Númenor, but rather that she was pointing out that in the Akallabêth, as in Genesis, you have the story of a society that is deeply sinful (or evil, if you prefer) and is utterly smitten by God (Eru), with only a few survivors... Lot & Daughters/Elendili.

Interestingly, and tying back to the main question, it seems to me that the Genesis story of Lot's company not being able to look back lest they turn to salt (as his wife did) is applicable to the original question of the thread title. Whether or not this is the point of Genesis, one could certainly say, literally, that Lot's family was not to turn back in any manner. In the same way, the utter destruction of Númenor utterly prevents any sort of a turning back. Elendil's family, like Lot's, can NEVER go back (although it is interesting to note, from the legend of Meneltarma rising above the waves and the many mariners that sought it, that the Dúnedain clearly tried).

Personally, I don't think the sinking of Númenor can be considered a lesson to Sauron. If Eru had wanted him punished, I'm pretty sure that the Ilúvatar could have done quite a bit worse to him. As for Ar-Pharazôn and his crew, they either died flat out or were imprisoned. In the former case, it's hardly a lesson since the dead can't apply the lesson, and in the latter case they probably never even found out.

That really only leaves the Elendili.