So…you’re agreeing with me?

No.

The Valar did not pass judgment upon Numenor as they were explicitly forbade from harming the Children. When the Great Armament landed on Aman, the Elder King laid down his right to call upon Eru to pass judgment on something utterly unprecedented. Prior to this, Manwe sent omens to warn the King’s Men of the Doom they would face if they continued upon the path of hubris.

Everything stems from Eru and it was Him that sunk Numenor as punishment. To morally debate the matter is effectively the same folly as Melkor sowing discord into the Music of the Ainur.

Eru may be god, but that doesn’t make him right.

How so? Can you explain how our concept of morality is superior to a transcendental, omnipotent being?

I’m not sure if one morality can be objectively considered to be superior to any other morality. To get along, we do need rules that most people agree on, and I think most people agree that it is wrong to kill innocents. Eru might disagree, but I think he would be in the minority.

It is also hard to see what right Eru has to punish anyone for anything when everything that happens is part of his plan. Surely, if he didn’t want the Numenoreans to turn against the Valar then they wouldn’t have.

Oh we most certainly rationalize concepts of morality being superior to others my friend. For much of humanity’s history there was a belief; by right of conquest, commerce, or competency, that the enslavement of others was ok.

In the context of the legendarium however, we are explicitly told that the only member of the Faithful that remained behind was Elendil’s father Amandil; whom sailed West in an effort to beseech the Valar for mercy on behalf of the King’s Men. That means the rest that did not follow the Faithful to the East were of the King’s Men and complicit in the sacrificial rites, enslavement of “lesser” Men, and breaching the Ban of the Valar by force.

Eru was not wont to directly intervene because that would prevent His children from exercising the free will he granted them. Manwë laid down the stewardship of Arda because he understood Eru’s will was not to harm His children despite their hubris driving them to be rid of the “Curse” through force. This is why His punishment was the reshaping of Arda, removal of Aman to a different plane of Eä, and the Drowning of Numenor. Such was depth of crime committed by that faction of the Secondborn; and Eru had every right because they had abused the Gift granted to them in a means that could threaten all of His creation.

There are so many less genocidal ways he could have handled that. He could have reshaped Arda without destroying Numenor. As you said, Numenor was a gift. You can’t call backsies once you give a gift.

You can when they abuse as the expense of other’s lives and teach future generations the same behavior. You must understand, it was not their call, they were warned, and their hubris drove them to militaristic aggression anyway.

Genocide would imply all the Men of Westernesse, and those of the Faithful were aided in their survival to land safely back on Middle-Earth.

That’s not how gifts work. When you give someone a gift, it no longer belongs to you. Eru and the Valar might have called Numenor a gift, but it seems that what they actually did was loan the island to the Numenoreans with conditions.