Some other notes:
(1) According to Swami Dayananda Saraswati, medieval commentators on the Vedas such as Sayan and Mahidhar and so also modern Vedic scholars in the West, had gone wrong in thinking that the Vedas taught idol worship. Au contraire, Saraswati taught unequivocally that the Vedas DID NOT teach polytheism and that it did not contain any mythological stories. Since the Vedas were eternal, they could not have any reference to historical or geographical happenings.
What then do we make of the apparent references to historical events in the Vedas – in the minds of scholars anyway? Saraswati does some exegetical gymnastics to explain them away. He is committed to priori exclusions of such references.
(2) Now it goes without saying that if you are a theist are oppose polytheism, then you more or less propose monotheism. And this is precisely what Dayananda Saraswati teaches. Actually he assumes this and claims that the references to godlike beings in the Vedas are really metaphors and such. An example of this is Agni.