Societies are made up of different individuals who vary in race, ethnicity and religion. Today, there is much talk about pluralistic societies and how can societal cohesion be promoted in such societies. The approach to Islam in this question is unique. In the process, it creates the strongest bond possible.
Before getting to a description of the strongest bond, it is important to note that Islam strikes at the very root of societal disunity: racism and prejudice. One can pass as many laws as one wills but as long as this disease is rooted in the heart, there can never be true social cohesion. Nothing highlights this fact more than the debates going on in Europe and the U.S. over immigration. Hatred for “foreigners,” even those who are full members and citizens of society, will always prevent true social cohesion.
Islam has wiped that disease away with one verse that indicates wherein one’s true worth lies. God has said:
“O mankind! We have created you from a male and a female, and made you into nations and tribes, that you may know one another. Verily, the most honorable of you with God is that (believer) who has piety and God-consciousness. Verily, God is All-Knowing, All-Aware.” (Quran 49:13)
Hence, race and ethnicity should have no effect whatsoever with respect to societal cohesion in the eyes of a Muslim. There is, though, a difference that Islam does take into consideration: the difference of faith and religion. Hence, this discussion of societal cohesion will be focused on societal cohesion in the context of a pluralistic society with respect to religion.
The Bond of Faith
If one were to ask many today as to what the strongest bond there could possibly be among people, most of them would probably answer something like blood relationship, ethnic origin, nationality and so forth. Actually, the Quran shows that these types of bonds are not that strong if the foundation behind them is weak. In the Quran, God gives the examples of Cain and Abel, who were two brothers yet one killed the other, as well as the example of the brethren of Joseph, who cast Joseph into a well. Those were all blood relatives; however, they put this world above their relationship with others. Such is occurring today throughout the world. The ties between the people are subservient to their desires, goals and wants of this world. Many individuals are quickly and easily willing to sell out their own kith and kin to get ahead in this world or to get something they want in this world.
All of this demonstrates one thing: When the ties between people are based on worldly considerations, even if they are originally blood ties, then those ties are given up when the worldly considerations so demand them to be given up. Hence, those are not the strongest ties that can be built among people. The strongest ties that can be achieved between people are the ties of Islam and true faith. These are the bonds forged between people that are solely the result of their belief in God and their love for God. This was clearly pointed out by God in the Quran when God stated:
“And He has united their (believers’) hearts. If you had spent all that is in the earth, you could not have united their hearts, but God has united them. Certainly, He is All-Mighty, All-Wise.” (Quran 8:63)
God also says:
“And hold fast, all of you together, to the Rope of God, and be not divided among yourselves, and remember God’s favor on you, for you were enemies and He joined your hearts together, so that by His grace, you became brethren and you were on a brink of a Pit of Fire, and He saved you from it. Thus God makes clear His signs to you, that you may be guided.” (Quran 3:103)
The Quran and the Sunnah show that the bond of faith is the strongest of all bonds. It represents humans from all over the world coming together for one purpose only: to establish the worship God alone. To achieve that goal, Muslims work together and help one another in compassion mercy and love.
There are actually numerous texts of the Quran and hadith that demonstrate beyond any doubt that Muslims are to form one universal, international brotherhood and sisterhood. For the sake of brevity, only a few examples of those texts will be presented here:
“The believers, men and women, are auliyaa (helpers, supporters, friends, protectors) of one another, they enjoining what is good and eradicate what is evil. They offer the prayers and pay the zakat and obey God and His Messenger. Surely, God will have His Mercy on them. Surely, God is All-Mighty, All-Wise.” (Quran 9:71)
Another verse reads:
“The believers are nothing else but brothers…” (Quran 49:10)
God also says:
“Muhammad is the Messenger of God, and those who are with him are severe against disbelievers and merciful among themselves…” (Quran 48:29)
The Prophet, may the mercy and blessings of God be upon him, said:
“The believer with respect to another believer is like a building, one portion strengthening the other.” (Saheeh al-Bukhari and Saheeh Muslim)
Another hadith states:
“The parable of the believers with respect to their love, mercy and compassion for one another is like that of the body: if one of its limbs is hurting, the remainder of the body is afflicted by sleeplessness and fever.” (Saheeh Muslim)
But this great brotherhood of Islam is not something simply theoretical. It is, in fact, well defined and supported by practical guidance. It has certain basic components to it and specific rights and obligations that are spelled out in the Quran and Sunnah. These rights and obligations are due to every Muslim, of every time and place.
 It is important to realize that this brotherhood is founded upon a common faith. In fact, blood relationships come to an end because of differences in religion. God says about Noah and his son, “[Noah said,] ‘O my Lord, verily my son is of my family! And certainly your promise is true, and You are the Most Just of the judges.’ He [God] said, ‘O Noah! Surely he is not of your family, his work is unrighteous’” (Quran 11:45-46). Hence, non-Muslims fall outside of the fold of this brotherhood. They are more than welcome to join this brotherhood by embracing Islam, as this brotherhood is not based on race, ethnicity or nationality. Otherwise, by their choice of religion and belief they have opted to remain outside of this brotherhood. As shall be discussed later, the Muslim still has obligations toward such non-Muslims.
 It is a great blessing that in Islam one finds detailed teachings that result in their desired goals while, at the same time, being extremely practical and consistent with human nature. The lack of such teachings is one of the greatest dilemmas faced by Christianity. With respect to societal cohesion, the greatest teachings found in the New Testament are what are known as “the hard sayings” of Jesus. They are as follows: “Ye have heard that it hath been said, An eye for an eye, and a tooth for a tooth: But I say unto you, That ye resist not evil: but whosoever shall smite thee on thy right cheek, turn to him the other also. And if any man will sue thee at the law, and take away thy coat, let him have thy cloak also. And whosoever shall compel thee to go a mile, go with him twain. Give to him that asketh thee, and from him that would borrow of thee turn not thou away. Ye have heard that it hath been said, Thou shalt love thy neighbour, and hate thine enemy. But I say unto you, Love your enemies, bless them that curse you, do good to them that hate you, and pray for them which despitefully use you, and persecute you; That ye may be the children of your Father which is in heaven: for he maketh his sun to rise on the evil and on the good, and sendeth rain on the just and on the unjust. For if ye love them which love you, what reward have ye? do not even the publicans the same? And if ye salute your brethren only, what do ye more than others? do not even the publicans so? Be ye therefore perfect, even as your Father which is in heaven is perfect” (Matthew 5:38-48). (Note that Muslims are well aware of the fact that Jesus’ words were not preserved properly and therefore one cannot truly argue that these were his words.) Christian scholars themselves are perplexed. How are such obviously impossible or impractical teachings to be applied? Just one example of a discussion of these words will suffice to show how perplexing they are: “[For interpreting these words, t]he model proposed by Joachim Jeremias is simple, representative, and of continuing influence. According to this model, the Sermon usually is seen in one of three ways: (1) as a perfectionist code, fully in line with the legalism of rabbinic Judaism; (2) as an impossible ideal, meant to drive the believer first to desperation, and then to trust in God's mercy; or (3) as an "interim ethic" meant for what was expected to be a brief period of waiting in the end time, and which is now obsolete. Jeremias adds his own fourth thesis: The Sermon is an indicative depiction of incipient life in the kingdom of God, which presupposes as its condition of possibility the experience of conversion. More complex or comprehensive schematizations have been offered, but most major interpreters can be understood in relation to the options posed by Jeremias.” Lisa Sowle Cahill, Love Your Enemies: Discipleship, Pacifism, and Just War Theory (Minneapolis, MN: Fortress Press, 1994), p. 27.