Disbelievers are 'slaves' of Allaah in the general sense
14-10-2014 | IslamWeb
Question:
Salaam Alaikum. I have another question about Islam. Who are the servants of God? Is every human being God's servant, or only those who follow God? Can polytheists be servants of God? Who are the slaves of God? Is every human being God's slave, or only those who follow God? Can polytheists be slaves of God? Thank you.
Answer:
All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad 
is His slave and Messenger.
The salves of Allaah may mean all that exists in the heavens and the earth, and so, the Muslims as well as the disbelievers, the pious as well as the dissolute are included in this; Allaah says (what means): {There is no one in the heavens and earth but that he comes to the Most Merciful as a servant.} [Quran 19:93]
The salves of Allaah may refer –especially – to the Muslims and believers, and on top of whom are the Prophets and Messengers, so the disbelievers and polytheists are not included amongst them; Allaah says (what means): {And the servants of the Most Merciful are those who walk upon the earth easily, and when the ignorant address them [harshly], they say [words of] peace.} [Quran 25:63]
Shaykh Hafeth ibn Ahmad al-Hakami said in his book A’laam as-Sunnah al-Manshoorah: “If the word slave refers to the one who is enslaved (subjected), then, it includes, in this sense, all the creatures of the worlds: the upper world [the world of angels] and the lower world [the creatures on earth]: whether sane or insane, moist or dry, mobile or static, apparent or hidden, believer or disbeliever, pious or dissolute, and so on. All are created by Allaah, the Almighty; they worship Him [as the One and Only true God], they are subjected to Him, and controlled by Him, and each one has a limit whereby he stops, and each of them exists according to an appointed term which they do not exceed by an atom; that is the determination of the Exalted in Might, the All-Knower. He is the only Disposer of affairs, the Just and the Wise. However, if with the term slave we refer to the worshiper who loves Allaah, and who humiliates himself to Him, then this refers specifically to the believers who are His honorable slaves and His pious allies, no fear will there be concerning them, nor will they grieve.” [End of quote]
Shaykh Ibn Uthaymeen 
said in his book entitled Al-Qawl al-Mufeed: "Slavery (servitude, being a slave to Allaah) is divided into three categories:
1- General: the slavery of worshipping the Creator, which applies to all creation; Allaah says (what means): {There is no one in the heavens and earth but that he comes to the Most Merciful as a servant.} [Quran 19:93] The disbelievers are included in this.
2- Special slavery: which is the slavery of general obedience, Allaah says (what means): {And the servants of the Most Merciful are those who walk upon the earth easily, and when the ignorant address them [harshly], they say [words of] peace.} [Quran 25:63]; this includes all who worship Allaah through His Legislation.
3- Specific type of special slavery, this is the slavery of the Messengers, may Allaah exalt their mention. Allaah says about Noah (what means): {Indeed, he was a grateful servant.} [Quran 17:3] Allaah says about Muhammad (what means): {And if you are in doubt about what We have sent down upon Our Servant [Muhammad]...} [Quran 2:23] Allaah says about other Prophets (what means): {And remember Our servants, Abraham, Isaac and Jacob - those of strength and [religious] vision.} [Quran 38:45]
This servitude (being a slave to Allaah) that is attributed to the Prophets is a special one because none can exceed them in being a slave to Allaah [as no one can excel them in worship].” [End of quote]
For more benefit, please refer to Fatwa 237517.
Allaah Knows best.