{Without doubt the believers are brothers of one another so then make peace and harmony between your brothers and have consciousness of Allah so that maybe He will show you mercy.}
The closest relationship and bond that can take place between two people during the course of their lifetime is that of brotherhood. Although the relationship between a father and his children is much stronger and powerful than the ties of brotherhood, however this relationship (between a father and his child) is one in which the two people are not on an equal level - from the point of view of time, situation, character and the level of respect (that they must show one another), they are different.
The only relationship that is a complete manifestation of strong unity, love and affection is the one that exists between two people who are living on an equal plane in life and this is the relationship of brotherhood and sisterhood.
This unbreakable relationship that has been brought about by creation is constantly found in all environments and societies and is the secret behind love, affection and closeness that exists between individuals. It is because of this fact that the Qur’an invites humanity to unite and come together under the principles of love and affection and thus, has referred to the faithful believers of a society as being brothers (and sisters) of one another.
For the first time in history, a community of people that numbered hundreds of millions was brought together as brothers of one another and the following sentence was made their slogan and motto:

إِنَّمٌا الْمُؤْمِنُونَ إِخْوَةٌ...

“Without doubt the believers are brothers of one another…”
You may ask yourself this question that why has this circle of relationship not been made wider and taken all of humanity into it as brothers of one another, whereas (in this verse) the sphere of brotherhood is limited to only those who have true faith? The answer to this question is obvious and a cursory glance is sufficient for us to understand the reason why this was not done.
This religious brotherhood is not a simple formality and that too of a political nature such that all of humanity – whether or not they have the qualities of brotherhood – should be classified and grouped together as brothers of one another. Rather, the purpose of making the believers brothers of one another points to a series of noble societal and ethical goals and responsibilities that take shape within the greatness of the Islamic brotherhood that the believers must manifest to one another.
All of these responsibilities and goals have been mentioned in the books of Ahadith and Jurisprudence in detail. Therefore, until unity of thought and spirit towards one goal and belief is not established, there can never be firm unity and association of individuals.
If one day, a group of people who are wavering (in belief) in their hearts are seen uniting together under a series of political issues and trying to unite as brothers for a specific cause (other than that of religion), then even the smallest thing would be able to break the unity that was brought about through the mere agreement of thoughts, spirits, difference of (personal benefits) and difference of foundations, and would thus cause them to separate from one another.
A society whose axis or pivot is not based on (unity of) ideas and beliefs and in which everyone acts as individuals will always rotate upon various thoughts and ideologies opposed to one another and no sort of unity or harmony will ever exist amongst those people. Only to that level that unity and harmony protects their material interests will they be able to lead a peaceful life. If one day a person who is united with others sees that he is not in need of this form of unity and feels that he has become successful in the arena of his own life and has reached his goals, then all of the relations that united him with others – which were all based on political motives – will be turned into differences and disputes.
Never would a Muslim - one who has true faith in One Allah and the Day of Judgement and who believes in the governance of justice and equality and who deems it necessary to follow the noble moral traits and the humanistic virtues - be able to become the brother of an atheist who does not believe in Allah (Glorified and Exalted is He) or the Last Day and who feels that ethical teachings and traits are just play-things and considers such teachings as fables.

Unity under the Luminance of True Belief
If we have doubts and misgivings about every issue among the issues within a society, or require that in order to acknowledge a specific issue that we must carry out analysis and research and claim the need to have proof (for these various issues), then we must not let these (doubts and misgivings) creep into the discussion of unity and harmony in the society. Thus, we can never find even a single person in this world who would say that dispersion and disarray (of the society) are beneficial and that unity and agreement are harmful and detrimental, since even the smallest benefit that can come about through unity and agreement returns back to the society.
It is through uniting small independent forces with one another that under the shadow of such unity can great power and strength come about which would be able to bring about numerous changes in the lives of people.
The huge dams of the world that manifest themselves as blocking large bodies of water are actually joining smaller bodies (of water) together since these small individual rivers do not have the ability to produce electricity, nor can they be beneficial for the irrigation of crops.
However, when all of these small rivers join to make one major body of water, then at this time they are able to produce thousands of kilowatts of electricity and it is through this one large river that thousands of hectares of land can be irrigated. Where do all of these great bounties come from? They come about through the unity of small drops of water that were once weak and did not possess the ability to do anything on their own.
The power of the atom is clear to everyone. A single atom does not have the power or ability to do anything and is so small and insignificant that even the most powerful microscopes cannot see what it looks like.
However when innumerable atoms join together, they produce such power and energy that if just a few atomic bombs were to be detonated, the civilization and life of mankind on this Earth, as we know it, would be brought to an end. In the span of a few minutes, the entire surface of the Earth would be a mass of fire with piles of ashes lingering everywhere.
In the words of a poet:

غرض ز انـجمن و اجـتماع جمع قواست
چرا كه قطره چـو شد مـتصل به هم درياست

The goal of union and coalition,
Is to gather the powers.
Since when drops of water gather,
Then they form a (powerful) river.

ز قطـره هيچ نيـايد ولى چو دريا گشت
هر آنـچه نفـع تصور کنی در او آن جـاست)

Nothing comes about from a drop (individual),
However the river (unity) runs strong.
Any benefit that can be imagined,
Comes about from that river (of unity).

ز قطره ماهی پيدا نـمى شود هر گز
مـحيط باشد كزوى نـهنگ خواهد ساخـت

A fish can never be seen,
In one single drop of water.
How is it then from the river,
Whales can come about.

زگندمی نتوان پخت نان و قوت نـمود
چو گشت خرمن و خروار وقت برگ و نواست

A loaf of bread can never be made ,
From a single head of wheat,
But when gathered together and thrashed,
It brings out all of its prosperity.

ز فرد فرد مـحالست کارهای بزرگ
ولی ز جمع توان خواست هر چه خواهی خواست

It is impossible for individuals - one by one,
To take on a great task.
However, from uniting together,
Anything that is desired can be accomplished.

بلی چو مورچگان را وفاق دست دهد
بـه قـول شيخ هـژبر ژيان اسـير و فنـاست

Unity and conciliation can be seen,
In the way that the ants gather together.
In the words of the Shaikh,
Glory is strong, captive and temporary.

ولى چو نفرقه اندر ميان جمع افتد
هـمان حکـايت صـوفى و سيـد و مـلاست

However when separation occurs,
To a community that is together.
They become just like the stories,
Of the Sufis, the Sayyid and the Mullah.
Not only must the physical strength of the people be made use of with everyone working towards one common goal, rather we must also seek assistance through the intelligence and aptitude of the members of society. Through taking advice, working together and accepting the opinions of others, we must remove the monstrous difficulties that are facing us.
The Noble Qur’an considers asking advice and (through this), changing one’s opinion as one of the characteristics of a person with true faith and has said:

وَالَّذِينَ اسْتَجٌابُوا لِرِبِّهِمْ وَ أَقٌامُوا الصَّلٌوةَ وَ أَمْرُهُمْ شُورَى بَيْنَهُمْ وَ مِمٌّا رَزَقْنٌاهُمْ يُنْفِقُونَ

“And those people who respond to the call of their Lord and who (also) uphold the Salat and proceed in their activities through consultation with one another and give out in charity of that which We have granted to them.”
The same point mentioned in the above verse of the Qur’an can also be seen in the poem previously quoted and also in the following two lines of poetry:

اگر مرا و تو عقل خويش كافى بود
چرا به امر خداوند، امر بر شورى است

If mine and your intelligence were enough,
Then why has Allah commanded us to consult (one another)?

بدين دليل ((يد اللٌّه مع الجماعة)) سرود
كه با جماعت، دستى قوی يدى طولـى است

We must resonate with the proof that: ‘The Hand of Allah is with the Congregation’.
Since by being with the community, The strong hand has a longer reach.

What is the Basis and Source of Unity?
A majority of Sociologists state that: “The human being is a societal animal and within his creation, he has been given a strong attraction to living within a community.” At this point, we must see that under what factors and conditions does our societal life take form?
Some of today’s Sociologists are of the firm belief that factors such as: race, language, sharing a common history and country, blood-ties and other elements make up the unity of nations. The society which is brought about through these elements just mentioned is the same one that the Legal Experts refer to as a Nation.
It is under the shadow of these factors that one is able to bring about a nation which is united in which the various organs and members, who are living in the midst of one another, can have a loving and close life together.
However these people (who have such a belief) have forgotten an important point: how is it possible for a society which is made up of people of various ideologies, who have different wishes and desires (for their own life) and who have their own opinions and thoughts in relation to every aspect, to come together as one united nation with complete harmony and live among one another in this form?
It is true that those factors which were mentioned do help and play a role in the unity and harmony of a society, however as long as there is no unity in thought and idea and each person has his own goals and ideologies, the unity and harmony of the individuals under these factors and principles will be involuntarily brought about and thus will not be permanent and stable.
If one day, the people were to unite under one common goal and stretch forth their hands towards one another in unity and express their brotherhood towards one another, then they would definitely be able to reach their goal. In this event, not a single event could occur that would cause them to fall into intellectual difference and discrepancy in relation to their wishes and goals - nor would they fall prey to conflicts and divergences that would lead them to be divided with one another.
A society whose axis does not rotate around one thought and ideology in which the people revolve around various factors that have been imposed upon them will never have a guaranteed unity (of the society) since the path of life of each person is determined through (one’s own) thoughts and ideological beliefs, and not factors that have been imposed upon one. If a day comes that amongst the people of a nation who share the same nationality, blood-ties and language - a spiritual bond and cultural affinity were to come about, then there could never be any sort of blow brought to the unity of that nation.
It is here that the great leaders of humanity – who take their inspiration from the Divine Revelation – have said that the foremost pillar of nationality must be based on unity of thought and ideology. The people of that society - who from the point of view of their ideological beliefs and method of thought share a common opinion – have been referred to as brothers of one another, and thus, their motto would be:

إِنَّمٌا الْمُؤْمِنُونَ إِخْوَةٌ...

“Without doubt the believers are brothers of one another…”
In his historical speech, the greatest leader of humanity, Prophet Muhammad (blessings of Allah be upon him and his progeny) categorized the people within a society who have true belief as being equivalent to the limbs of one body, such that they all share one common thought and ideology, one soul that commands and governs over them and whose hearts are united.
In summary, the material factors which contain absolutely no soul or essence such as: nationality, language, blood (relation) and others which cannot build unity of thought and which are not from those things which the human soul has been inspired with, cannot bring about the basis by which nationality and the principles of a common life are based upon and which can lead to one united nation of people – which have complete love and close friendship and unity amongst the individuals. Rather, individuals that are brought together under the banner of these factors - due to the difference of thoughts and their divergence in distinguishing their goals - will give up any sort of unity and alliance that they have amongst one another.
In addition to this, the person who wishes to build a nation under the flag of these sorts of material factors can never claim that with these factors in place, they have been able to bring all of humanity as brothers of one another, nor will they be able to claim that the entire society has become spiritually close.
Rather, the only claim they would be able to bring is that they have been able to unite a large number of people (not all) together under certain incidental phenomena (those factors which were previously mentioned).
If the sublime Prophet of Islam (blessings of Allah be upon him and his progeny) was able to bring the hearts of various groups of people together and bring people of various nations - each of which had their own nationality and language - together as one nation and make them brothers of one another, then he was able to do so because he was able to bring about one common united thought and ideology amongst them all. In addition, the direction of all of their lives was geared towards one goal and all of their ideas and thoughts were channelled into one main thought.

آفرين بر همت آن اوستاد صد هزاران ذره را داد اتـحاد

Congratulations to the efforts of that one leader, Who brought unity to hundreds of thousands of individual minds.

An Effective Medication
On the day that the Prophet (blessings of Allah be upon him and his progeny) was commanded to convey the Heavenly messages of Allah (Glorified and Exalted is He), we see that the environment of the Muslims in Madinah was plagued with differences. It was not possible to restore back to health the sickness of division that had plagued the community, except by going under the banner of unanimity, accord and unity of thought.
The Muhajirin and the Ansar had been brought up in two completely different environments and each of them felt some sort of supremacy over the other group, while the Ansar themselves were divided into two factions which had the fires of war raging between them for years. The Muslims who had come from places far and wide such as Habasha (Ethiopa) and other parts of the world suddenly converged on the land of Madinah.
From the point of view of their nationality and language, a majority of them differed from one another. The most powerful of relations that existed amongst all these people - keeping in mind the differences that were also there - was the relationship of true faith and religious brotherhood through which the enmity, hatred and other negative effects that their differences created amongst themselves, was removed from their hearts.
One day, the Prophet of Islam (blessings of Allah be upon him and his progeny) stood up in the Masjid, turned towards the Muslims and said:

تَآخَوْا فِي اللٌّهِ أَخَوَينِ أَخَوَينِ

“(O’ people Stand up so that I can make you brothers of one another (in the name of Allah).”
Upon hearing this, the Muslims stood up and each one was made a brother of another one whom they had a great deal of love and affection for and it was here that the Prophet of Islam (blessings of Allah be upon him and his progeny) chose Amir al-Mu’minin `Ali ibn Abi Talib (peace be upon him) as his own brother.
This sort of brotherhood which took place amongst a very small circle of people is a minor example of the unity that ruled over the Islamic society which encompassed all Muslims and made them brothers of one another. Under the greatness of this Islamic brotherhood, the Muslims were victorious over all of their difficulties and as long as this religious bond of love and affinity was amongst them, they had supremacy over the entire world.

An Alert Enemy
The enemies, who at that time were desperately seeking the down-fall of the Muslims, struggled and are continuing to struggle (even today) to cut the firm roots of unity from amongst the Muslims and to remove this affinity from the Muslim nation. By bringing up a series of issues which are not related to the fundamental principles (of the religion), they have been able to light the fire of difference amongst the Muslims. This is not only the goal of the enemies of our present time - rather, from that first day that this Islamic commandment was given, those who wanted bad things to come to the Muslims struggled to break the unity and accord.
One day, a group of young men from the tribes of Aws and Khazraj (two tribes from `Arabia that had been at war for countless years, however under the shadow of Islam and true faith, were able to come together as brothers of one another and have love rule between them both) were sitting together.
A Jew from Madinah named Shas ibn Qais who was very jealous of the unity that had been brought about between these two tribes, entered into their gathering and through the shrewdness that he possessed, started to speak about and remind them about the bitter moments that had transpired between these two tribes during the battle of Ba`ath before the coming of Islam. He spoke in such a manner that he was able to instigate the youth of both tribes to reach for their swords causing them to re-ignite the war of Ba`ath.
The Prophet (blessings of Allah be upon him and his progeny) was informed of what was transpiring and he himself went to this gathering and gave a speech in which he mentioned, “Islam made you brothers of one another and commanded you to remove any form of hatred or grudges that remain in your heart.”
When the speech of the Prophet reached to this phase, the deafening sound of crying and weeping could be heard and in order to attest to the religious brotherhood that existed amongst themselves, they began to hug each other and asked Allah (Glorified and Exalted is He) for forgiveness.
If on that day a man named Shas existed (that caused such turmoil), then today too there are those who under different names, different physiognomies and different shapes are trying to stir up corruption within the Muslim society. It is these people who are trying to strike devastating blows to the unity and harmony of the Muslims.

Examples of Self-Sacrifice through Islamic Brotherhood
One of the greatest manifestations and materializations of brotherhood is that a Muslim does not encroach upon the life, reputation and wealth of his brother.
This point has been mentioned in one of the valuable pieces of advice from the Messenger of Allah (blessings of Allah be upon him and his progeny) which he delivered to a large gathering of people in Mina. In this assembly, he turned towards his companions and addressed them as such: “(O’ People
Today is a day which is very sacred in the sight of your Lord and this land of Mina too is one of sanctity and this month (Dhul Hijjah) which we are presently in, is a noble month in the sight of Allah!”

إِنَّ دِمٌائَكُمْ وَ أَمْوٌالَكُمْ وَ أَعْرٌاضَكُمْ عَلَيْكُمْ حَرٌامٌ كَحُرْمَةِ يَوْمِكُمْ هٌـذَا وَ بَلَدِكُمْ هٌـذَا وَ شَهْرِكُمْ هٌـذَا

“Unquestionably your lives and your properties and your reputations are all sacred and sacrosanct just as this day of yours, this land of yours and this month of yours (are sacred).”
The Prophet repeated this sentence three times and then looked towards the sky and said:

أَللٌّهُمَّ بَلَّغْتُ

“O’ Allah (You bear witness that) I have (fulfilled my responsibility and) conveyed the message.”
In order to nurture and cultivate this spiritual relationship, Islam has laid down commandments through which the Muslims are able to make their brotherhood and love for one another known (to one another) in a practical manner.
There was once a man in the Masjid of the Prophet (blessings of Allah be upon him and his progeny) who asked Imam Muhammad ibn `Ali al-Baqir (peace be upon him), “I am this man’s friend (pointing to the person beside him).” The Imam replied, “Show the level of your friendship to him, because by expressing your love and friendship for a person, you will make the relationship last (longer).”
The words of the leaders of Islam (the Prophet and A’immah) in making this religious affinity strong are so many in number than we would not even be able to bring forth one-tenth of them (in this book), however from amongst all of these narrations and commandments, we present two traditions. The Prophet of Islam (blessings of Allah be upon him and his progeny) has said:

إِنَّمٌا الْمُؤْمِنُونَ فِي تَرٌاحُمِهِمْ وَ تَعٌاطُفِهِمْ بِمَنْـزِلَةِ الْجَسَدِ الْوٌاحِدِ إِذٌا اشْتَكى مِنْهُ عُضْوٌ وٌاحِدٌ تَدٌاعى لَهُ سٌائِرُ الْجَسَدِ بِالْحِمى وَالسَّهَرِ

“Surely the believers – in relation to the mercy and compassion and affection (that they show for one another) - are the same as one body. Therefore, if one part of the body is feeling pain, then it complains about this pain to the other parts of the body through a fear and hurt (so that the body can help the hurt or injured part).”
Therefore, any time a Muslim is facing troubles or difficulties, it is incumbent upon all the individuals of the society to rush to his aid and to also share in his grief.
Sa`di, the gifted poet and brilliant orator from Shiraz has taken inspiration from this hadith and expressed it in the following poem:
The Children of Adam are related to one another, And in their creation, they are all from one essence.
If one part of the body falls into pain and suffering, Then all other parts of the body are also affected.
In the second hadith, the Prophet of Islam (blessings of Allah be upon him and his progeny) has said:

أَلْمُسْلِمُونَ تَتَكٌافِـيءُ دِمٌــاؤُهُمْ وَ تَسْعـى بِذِمَّتِهِمْ أَدْنٌاهُمْ وَ هُمْ يَدٌ عَلى مَنْ سِوٌاهُمْ

“The worth of the blood (the lives) of the Muslims is equal to another Muslim and even the smallest trust that is given from one of them to another must be honoured, and in the face of foreigners (enemies) they are all united together and are one force (against the opponents).”
We suffice with these two hadith in relation to Islamic brotherhood, which is one of the most essential principles of Islam for the Muslims. Later on, the rights of a believer over his brother will be mentioned.
In truth, we are able to say that the closest relationship and firmest link which can exist within a society and which will never be broken - is the religious affinity which covers all boundaries of status, racial diversity and spiritual levels and we must struggle to maintain this benefit that the religion has given us.
Yes! In the words of the Qur’an, that which has brought about this religious affinity is the Islamic brotherhood. An everlasting peace and harmony can never be brought forth except through this commandment.
One of the necessary criteria for religious brotherhood is that whenever two groups of Muslims fall into disagreement with one another, it is necessary for all of the believers to struggle and try to put out the flames of war between them and to raise the flag of peace and agreement over them. However, Islam is not hell-bent on achieving peace at any cost. Rather, Islam wants peace on the basis of justice and equality and one in which the rights of both sides are protected and thus, the following verse of the Qur’an mentions:

فَأَصْلِحُوا بَيْنَهُمٌا بِالْعَدْلِ...

“So then make peace between the two parties with justice…”
If this is not done, then a peace treaty or any other sort of agreement which tramples upon the rights of one of the two parties would not be a long lasting one. Rather, it would lay the groundwork for enmity and hostility which is not looked upon favourably by the teachings of Islam.