There is a god of the Tolkien universe. His name is Eru Ilúvatar.

Arda is the planet that Middle Earth is on (with Middle Earth being a continent)

Sauron is the main enemy in the LOTR trilogy

Númenor was an island that the Valar (sub-dieties under Eru) created for men that helped in the fight against Melkor (also known as Morgoth), a Valar that turned evil and who was the boss of Sauron for a long time.

The inhabitants of the island were blessed with long life, good health, etc, and their culture was very elven-inspired. Much of the upper class was part elven, even.

Sauron tricked many of the Numenoreans to join his cause and take a fight to the other Valar, saying it'd give them immortality. Eru got angry, destroyed the island and reshaped Arda from flat to a sphere.