Muslims love to accuse other religious groups of idolatry, polytheism, shirk, etc. The Qur'an calls idolaters "the worst of creatures" (98:6) and even accuses Christians and Jews of associating partners with Allah (9:30). Indeed, Muslims are commanded to violently subjugate Christians and Jews because of our beliefs (9:29).
Apparently, Muslims are so busy accusing other people of idolatry, they haven't bothered to examine their own religion. The following video shows that Muslims have deified Muhammad. Thus, by their own standards, Muslims are idolaters and not true monotheists.
For more on Islam's deification of Muhammad, see the following articles: