The Satan essentially received his power from a source of holiness, because nothing can exist in the world unless it in some way draws on holiness. Holiness is true substance and everything in the world must have some spark of it to survive. Holiness is that substance which G-d infuses into beings to give it existence. Therefore, the Satan also requires holiness. Through the seven original mitzvos of Noach, non-Jews can get spiritual strength and merit in this world. When a non-Jew is born into a certain nation and he has that spiritual strength, he already has described to a certain degree what accomplishment he's going to have. A non-Jew who merits the World to Come is different that a Jew who merits the World to Come.