How is it not contradictory, though, to say, "There is nothing but God," and to speak also of "deception and ambiguous doublespeak," "mind viruses," "autonomous mental complexes of ignorance," and so on?

Don't you want to say that there's God and there's the illusion of the idols that are mistaken for gods? Illusions or idols aren't nothing, though. They may be nothing in comparison with your God's grandeur, but that would be a value assessment, not a metaphysical point.