Question: Does everyone who commits ash-Shirk al-Akbar (the association of a partner in worship with Allaah on a major level) become a mushrik, and thereby the (appropriate) rulings pertaining to the mushrikeen are applied upon them?
Answer: Yes. Whoever disbelieves in Allaah becomes a kaafir, and whoever commits shirk with Allaah becomes a mushrik; Just as whoever believes in Allaah and His Messenger becomes a believer (mu.min) and muwahhid (one who attests to the Oneness of Allaah).
As for he to whom the (Islaamic) da’wah has not been conveyed, then it is not said of him that he is a believer and nor a kaafir, and he is not to be dealt with as a Muslim, rather his affair is with Allaah on the Day of Resurrection, and they are those who are unaware since the (Islaamic) da’wah has not been conveyed to them, they shall (instead) be tested on the Day of Resurrection.
As for him to whom the (Islaamic) da’wah has been conveyed and he has (subsequently) not believed and become a Muslim, then he is a kaafir and an enemy of Allaah.
by Ibn Baaz (may Allah have mercy on him)
Silsilah Kitaab ad-Da ‘wah (11), al-Fataawa – Volume 4, Page 3