As you correctly quoted Elder McConkie, we regard ourselves as monotheists, and not as polytheists (see p. 49). By that we mean that we believe in one God. God the Father, his son Jesus Christ, and the Holy Ghost are three separate and distinct divine beings. You can call them "Gods" if you want. But they are united in purpose, in thought, and in power; in all things they act as one. Therefore it is entirely correct to call them "one God."
It is entirely incorrect, and more than a little uncharitable, to accuse Elder McConkie of playing "word games" when he points this out (p. 49). If you have ever spoken to Muslims on this subject, you would discover that they think that all Christians are playing "word games" when we claim to be monotheists, while believing that Jesus can be fully divine, but a different person from his Father. And those who are astute enough to distinguish the rather small (from their point of view) differences between mainstream creedal trinitarianism and LDS precreedal trinitarianism will generally remark that ours just seems less murky.
When Elder McConkie elsewhere says, "But in addition there is an infinite number of holy personages, drawn from worlds without number, who have passed on to exaltation and are thus gods" (p. 49, from Mormon Doctrine, 576–77), that is not a polytheistic statement. For my dictionary defines polytheism as "the worship of more than one god." Leaving aside our "trinitarian" differences for a moment, you must see that the mere acknowledgment that other gods exist entirely out of our reckoning is a far cry from any known form of polytheism. No worship of any of these beings is contemplated even for a moment. Neither can we be said to even "believe in" them in any meaningful way; we simply indicate that they are "somewhere out there," like quarks or pulsars, but they make no difference to us at all. Our religion would be exactly the same without them—because it is, in fact, without them. They do not figure in our worship or in our religious life at all. They are a mere academic detail.
When we consider that every known polytheistic system includes the names of the multiple gods, their relationships with one another, and their various powers, interests, or "departments"— and then find that all these features are completely absent from Latter-day Saint belief—it becomes apparent that calling our belief "polytheism" is not very meaningful and could be seen as a simple insult.
So your statement, "we see the first major difference between Mormonism and Christianity—monotheism versus polytheism" (p. 49), contains two false dichotomies. Once again, I notice that you are using Christian and Mormon as mutually exclusive terms. They are not, and you seem to be loading the dice when you use them in this way.
