As a yardstick and criterion in our lives, Islam has given us a clear definition of unity and brotherhood and how it can be realized and implemented.  The uniting factor is the `Aqeedah (creed) of Islam which defines the belief of a Muslim.  Unlike other bonds (nationalistic, patriotic, etc.) which are superficial, animalistic, reactive, emotional, and completely devoid of a real solution for life’s affairs, the intellectuality of the ideological bond of Islam unites man irrespective of their race, nationality, and other factors which are irrelevant when it comes to bonding on an ideological creed.

Allah in the Qur’an describes what is unity in Islam as the Mu’minoon (Believers; those that believe in Allah and His Messenger Muhammad) being united in a Brotherhood based on solely Islam:

“The Mu’minoon are but a single Brotherhood.” (The Holy Qur’an, 49:10)

Allah further defines this Brotherhood by explaining that Muslims are awliyyaa’ (allies, friends, supporters) of one another, and this again is based solely on Islam:

“The Believers, men and women, are protectors one of another: they enjoin the ma`roof (all of Islam), and forbid the munkar (all that is evil; kufr): they observe regular prayers, pay Zakat, and obey Allah and His Messenger. On them will Allah pour His mercy: for Allah is Exalted in power, Wise.” (The Holy Qur’an, 9:71)

Muhammad (Salla Allahu `alaihi wa sallam) indicated in several Ahadith on unity and brotherhood as we can see in his (saaws) Farewell Sermon (khuTbat ul-wadaa`):

“All mankind is from Adam and Eve, an Arab has no superiority over a non-Arab nor a non-Arab has any superiority over an Arab; also a white has no superiority over black nor a black has any superiority over white except by piety and good action. Learn that every Muslim is a brother to every Muslim and that the Muslims constitute one brotherhood.”

Other Ahadith further elaborate on the concept of unity and brotherhood:

"A Muslim is the brother of another Muslim. He does not oppress him, nor does he leave him at the mercy of others." (Sahih Muslim Book 032, Number 6219)

The Prophet said, "None of you will have faith till he wishes for his (Muslim) brother what he likes for himself." (Sahih Al-Bukhari Volume 1, Book 2, Number 12)

As the teachings of Islam clearly show us that Brotherhood and unity in Islam are based solely on the `Aqeedah of Islam (which is the foundation of Muslim belief).  The Mu’minoon are believers to one another and this belief has nothing to do with race or any other type of invalid reason to unite but is rather a bond based on an ideological belief in Islam.