Islam and Shirk, in their true meanings, are complete opposites. Their meanings are explained absolutely clearly in the Qur’an and Sunnah – about this there is a consensus. So he who commits Shirk does not fulfill the basis of Islam.
How can one who commits Shirk fulfill the basis of Islam, when this very basis is to leave all Shirk and dedicate all your worship to Allah alone? Therefore whoever commits Shirk can never be a Muslim? One is either Muslim or Mushrik, a third group does not exist! Islam means, in the consensus of the scholars of language and Tafseer and all other scholars “to completely submit oneself under the Will of Allah”, so including the humility, submission and obedience. Allah the Almighty says:
“Yes, but whoever submits his face (whole self) to Allah (performs his deeds free from Shirk, purely for Allah) and he is a Muhsin (is a doer of good) then his reward is with his Lord (Allah), on such shall be no fear, nor shall they grieve.” (Baqarah 2:112)
At-Tabary narrates from some of the Salaf as follows: “That they said, “He who submits his whole self to Allah” means “Akhlasa lillah” (that he does it purely for Allah alone, free from Shirk, submitting himself only to Allah).” He said further: “Like Zaid ibnu Amr ibn an-Nufail also said: “I have surrendered my face (my whole self) to Him (purified it completely from all other), to Whom the clouds carrying pure water also surrendered.”
Meaning here, “I have submitted myself to His obedience, to Whose obedience the clouds have also submitted and Whose orders they follow.”
In this Ayah (2:112) Allah the Almighty mentions those who submit their faces alone to Allah. Mentioning the face here has been given preference to over the rest of the body because the most precious, important and worth protecting part of the body is the face. When a person submits his face, his most precious part of the body, to something or someone then the rest of the body naturally follows in submission. For the Arabs it was logical (linguistically) that when they mentioned the face it meant the body as a whole.
So the Ayah means “Nay, whoever obeys and worships Allah purely (free from Shirk) for Allah alone and carries it out in the best manner…” As also stated and thoroughly explained by Ibnu Katheer. Hence, Islam means, in the consensus, to surrender in worshipping Allah alone with submission without associating anything with Him. Whosoever does not do this can never be a Muslim, upon this they are all in agreement. And how else can it be? Let us demonstrate this by means of an example: A man never rides a horse, instead always walks by foot and he also never did ride, how could a rational and reasonable thinking person call him an equestrian (one who rides a horse)? Similarly, a person who never submitted himself to Allah alone, and attributed others to Him, someone who never worshipped Him sincerely and still does not do it, such a person cannot be described as a Muslim. He does not possess the characteristics required in Islam which would make him to a Muslim and his deeds are not according to the deeds of a Muslim. No one who has a common sense would define him as a Muslim.
Ibnu Taymiyyah, may Allah be merciful to him, says in Majmu‟ ul-Fataawa 14:282, 284: “And so anyone who does not worship Allah, must undoubtedly be worshipping something other than Him; he worships someone other than Him and is therefore a Mushrik. Among the sons of Adam there is no third part. There is only Muwahhid and Mushrik or those who combine both parts like the distorters of the followers of different religions and the Christians and those who have gone astray who consider themselves to be within Islam”.
He who reflects over this passage, will find that Shaykh ul-Islam says five times, each time in a different way that someone who commits Shirk can never be a Muslim. Is there something clearer than that?
Shaykh Abd ur-Rahman says in his work “Explanation of the principle of Islam and its most important pillar” and Abd ul-Latif says in Minhaaj (pg. 12): “He who commits Shirk, leaves Tawheed for they are two opposites which never come together and can never cancel each other out.”
When Islam departs, Shirk must take its place whereas it is irrelevant why Islam departed. And who does not know this, has not understood Islam.