Discussing historical facts or jurisprudential differences should not in any way discourage Muslim unity, since the majority of Muslim historians from all schools of thought agree on similar historical facts. Differences between the philosophers, scholars and thinkers of the schools of thought can be either constructive or destructive. If they lead to the fragmentation of the Muslim nation, then they are unacceptable, as the Noble Qur’an says,
“But they have broken their religion among them into sects, each group rejoicing in its belief.”1
Such groups of people support ideas which are not based on the truth and use them only to serve their own purposes, whereas the Noble Qur’an refers all arguments to one source,
“And obey Allah and His Messenger, and do not dispute with one another lest you lose courage, and your strength depart, and be patient; surely, Allah is with those who are patient.”2
Unfortunately, the weakness of the Muslim world today is because of this type of disunity. Nonetheless, constructive differences is a sign of a healthy society in which people compete for what is best,
“If Allah willed, He would have made you one nation (religion) but that He may test you in what He has given you. So strive (as in a race) in good deeds.”3
Differences in scientific and jurisprudential opinions can lead to progress and prosperity, and on a philosophical level, they are beneficial if they lead to certainty (yaqeen), since all people must doubt, question, and differ from a matter before arriving at the truth. Therefore, Islam does not reject reasoning in the field of jurisprudence (ijtihad), as long as it is not contaminated with politics or personal aims and conceit. Thus all Muslim scholars agree that mujtahid (juristic scholar) receives two rewards for every correct decision, and at least one for every incorrect one because he is endeavoring with all of his effort to reach the correct decision.
Nevertheless, Muslim unity is one of the goals of Muslim society and is an obligation upon all Muslims, both individually and collectively. Allah says in the Noble Qur’an,
“Truly, your nation is one united nation, and I am your Lord,”4
and
“Verily this (your nation) is one nation, and I am your Lord, so uphold your duty to Me.”5
Throughout the twenty-three years of his propagation, the Messenger of Allah emphasized the unity of his nation and called them “My Nation (Ummati).” The Noble Qur’an gives six meanings for the word ummah: a group of people, an example, adherence to a religion, a religion itself, the time, and a group that follows one tradition and one way. However, it is not used for a group that does not follow one tradition and one way.
The concept of unity itself is discussed in the Noble Qur’an on three levels. Foremost, it is the unity of humanity,
“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 Allah is the one who has piety.”6
The aim of this unity is to direct all the racial, tribal, and religious differences into a constructive direction. Thus the emphasis on “knowing one another” (li-ta‘arifu) is that people should find mutual understanding rather than conflict, so that no one is denied the rights for life and prosperity.
The second form is within the unity of the People of the Book (or the monotheistic religions), for which the Qur’an says,
“Say (O Prophet Muhammad): O People of the Book! Come to a word that is just between us and you, that we worship none but Allah, and that we associate no partners with Him, and that none of us will take others as lords besides Allah. Then if they turn away, say: Bear witness that we are Muslims.”7
The Noble Qur’an reiterates that the People of the Book were asked to worship only Allah,
“And they were commanded not, except that they should worship Allah and worship none but Him alone.”8
The essential monotheistic unity of the People of the Book exists, but it should not be taken to mean that there are no differences between their rules and laws and that of Islam’s. While the original way (din/religion) is seen throughout all monotheistic religions, the practical implementation—i.e. the law—is different according to the Qur’an,
“To each among you We have prescribed a law, and a clear way. If Allah willed, He would have made you one nation but [His purposes require] that He test you in respect to what He has given you.”9
Of course, the third unity that the Noble Qur’an speaks of is the unity of the Muslim nation,
“And hold fast, all of you together, to the rope of Allah, and be not divided among yourselves.”10
Muslim unity has two fundamental purposes - one is to uphold the Noble Qur’an as the constitution of life, and second, is to accept our mutual responsibility towards each other as Muslims, for the Messenger of Allah has said, “Whoever does not care about the affairs of the Muslims is not one of them,” and “Whoever hears a man calling ‘O Muslims!’ and does not respond is not a Muslim.” He also used the parable of the human body to describe the Muslim nation - if one part suffers, the entire body will suffer. One of the greatest achievements of the Messenger of Allah was to unite hundreds of fragmented tribes throughout the Arabian Peninsula into a single strong nation.
When he united them, he did not eliminate differences of opinion between them, but rather, he enabled them to have dialogue with each other and to come to a sense of mutual understanding. Under this philosophy, the Muslim nation was a powerful nation in the past, and only with this understanding it would be able to return to this respected position among the nations of the Muslim world and have the same significant role that it did in the past.
A modern example that the Muslim countries should examine is the European Union in which several states of different languages, cultures, ethnicities, religions, and political agendas have unified under one monetary system, economic agenda, and political front. The Muslim governments could be similarly united if they so chose. The first step to such a unity is to increase the regular conferences and seminars which are held by Muslim intellectuals and scholars and aim to bridge the gap between the schools of thought.
In short, differences of opinion, when properly channelled, are an asset to the intellectual growth of the Muslim nation and are a sign of the vitality of the Islamic culture. The competition arising between different scholars, from all schools of thought, should encourage them to strive with their maximum effort to reach the best decisions, and ultimately, the truth. Diversity should not lead to division and fragmentation; on the contrary, it is part of the unity, just as it was in the society created by the Messenger of Allah 1,400 years ago.
We would like to encourage all the scholars and intellectuals of Islam to continue the discussions on the juristic and philosophical issues under the umbrella of la ilaha illa Allah Muhammadar rasul Allah (There is no entity worthy of worship except for Allah and Muhammad is the Messenger of Allah), and with the spirit of brotherhood and faith. And ultimately, we ask Allah, the Almighty for His guidance and wisdom.
O you who believe! Fear Allah as He should be feared, and die not except in a state of Islam (submission to Allah). And hold fast—all of you together—to the rope of Allah, and be not divided among yourselves, and remember Allah’s favor on you, for you were enemies, one unto another, but He joined your hearts together so that by His grace you became brethren. And you were on the brink of a pit of fire, and He saved you from it.
Thus Allah makes His signs clear to you, that you may be guided. Let there arise out of you a group of people inviting to all that is good, enjoining the good and forbidding the evil, and it is they who are the successful. And be not as those who divided and differed among themselves after the clear proofs had come to them. It is they for whom there is an awful torment on the Day when some faces will become white, and some faces will become dark. As for those whose faces will become dark (to them it will be said),
“Did you reject faith after accepting it? Then taste the torment for rejecting faith.”
And as for those whose faces will become white, they will be in Allah’s mercy. Therein they shall dwell forever. These are the verses of Allah. We recite them to you in truth, and Allah wills no injustice to mankind.11

References
1. Noble Qur’an, 23:53
2. Noble Qur’an, 8:46
3. Noble Qur’an, 5:48
4. Noble Qur’an, 21:92
5. Noble Qur’an, 23:52
6. Noble Qur’an, 49:13
7. Noble Qur’an, 3:64
8. Noble Qur’an, 98:5
9. Noble Qur’an, 5:48
10. Noble Qur’an, 3:103
11. Noble Qur’an, 3.102:108