Why did Sauron think he could succeed?
Yes, I know he thought the Valar were “done” with Middle Earth; he was a self deluded “atheist” per Tolkien (self deluded in that he had literally been in the presence of God).
But how was he certain that the Valar were not simply waiting for the right moment to intervene?
Or didn’t see that Olorin was a being of his own nature, as was Saruman; he had to know they had been sent by the Valar?