[Boromir88]

Hello Zigur, welcome to the Barrow-downs. A highly interesting thread topic, and much of what you say is what I think as well.

"Opportunist" is a good word to use for Sauron. I can't track down the precsie reference at the moment, but Sauron first was drawn to Melkor's service because of Melkor's power and the expediency he was able to enact his plans. Morgoth seemed the "I want this now" Dark-Lord, where Sauron was more calculated and thoughtful:

Sauron, however, inherited the 'corruption' of Arda, and only spent his (much more limited) power on the Rings; for it was the creatures of earth, in their minds and wills, that he desired to dominate. In this way, Sauron was also wiser than Melkor-Morgoth. Sauron was not a beginner of discord; and he probably knew more of the 'Music' than did Melkor, whose mind had always been filled with his own plans and devices, and gave little attention to other things.~HoME X: Morgoth's Ring; Myths Transformed

Sauron, no doubt, joined Melkor's service because they essentially had the same designs. But it was an opportunistic move, much like Saruman's "we can join with that Power (Sauron)" speech to Gandalf was Saruman being an opportunist. Saruman expresses the same goals as Sauron, but feels to achieve them, the easiest way is to get on Sauron's good side, and then backstab him when the chance presented itself. I'm not saying Sauron ever wanted to backstab Morgoth, but he joined Morgoth to further his own ambitions.

Eventually, Morgoth starts slipping into nihilism, where all he cares about is complete and utter destruction. Morgoth, being unable to control becomes like an 8-yo having a temper tantrum. "Fine, if I can't have it my way, I'm just going to trash the place." He recklessly throws in armies and spends resources, because all he wants total destruction. On the other hand, Sauron never falls to nihilism:

"He [Sauron] still had the relics of positive purposes, that descended from the good of the nature in which he began: it had been his virtue (and therefore also the cause of his fall, and of his relapse) that he loved order and co- ordination, and disliked all confusion and wasteful friction. (It was the apparent will and power of Melkor to effect his designs quickly and masterfully that had first attracted Sauron to him.)"~ibid

And take care of two points with one quote, since I also found the reference to why Sauron first joined Morgoth. Anyway, Sauron loved order and co-ordination. His plans were to dominate and control free will. He wanted slavery and obediance to his will. Morgoth wanted to burn the world. It's hard to rule over others if you're destroying/killing everything.

As far as the Melkor-religion he was creating in Numenor. Again, this is, I feel, Sauron just being an opportunist:

Sauron was not a ’sincere’ atheist, but he preached atheism, because it weakened resistance to himself (and he had ceased to fear God’s action in Arda)..... To wean one of the God-fearing from their allegiance it is best to propound another unseen object of allegiance and another hope of benefits; propound to him a Lord who will sanction what he desires and not forbid it. Sauron, apparently a defeated rival for world-power, now a mere hostage, can hardly propound himself; but as the former servant and disciple of Melkor, the worship of Melkor will raise him from hostage to high priest.~ibid

Sauron never denies the existance of the "Gods" and from the sound of it, never aligned to the belief of Morgoth idolatry. He ceases to fear they will step in and muck up his plans, as they had done with Morgoths, but he always acknowledged their existance. Sauron's Melkor-religion of Numenor, was Sauron wisely recognizing it strengthened his own standing in Numenor, not that he actually believed it:

When he found how greatly his knowledge was admired by all other rational creatures and how easy it was to influence them, his pride became boundless. By the end of the Second Age he assumed the position of Morgoth's representative. By the end of the Third Age he claimed to be Morgoth returned.~Letter 183

Technically speaking, he is following along with Morgoth's work, because Morgoth was the creator of all this discord. However, Sauron was full of pride, and I think we can reasonably say, in Sauron's mind (which is what really matters here), he's not thinking about Morgoth. He's thinking about his own abitions, and setting himself as the "Lord" over Middle-earth.