The well-being of mankind, its peace and security, are unattainable unless and until its unity is firmly established.
(Baha’u’llah: Gleanings, p. 286)

It is incumbent upon all the peoples of the world to reconcile their differences, and, with perfect unity and peace, abide beneath the shadow of the Tree of His care and loving-kindness.
(Baha’u’llah: Gleanings, p. 6)

The world is in greatest need of international peace. Until it is established, mankind will not attain composure and tranquillity.
(`Abdu’l-Baha: Promulgation of Universal Peace, p. 301)

Today there is no greater glory for man than that of service in the cause of the Most Great Peace. Peace is light, whereas war is darkness. Peace is life; war is death. Peace is guidance; war is error. Peace is the foundation of God; war is a satanic institution. Peace is the illumination of the world of humanity; war is the destroyer of human foundations.
(`Abdu’l-Baha: Promulgation of Universal Peace, p. 123)

The Role of Religion:
God’s purpose in sending His Prophets unto men is twofold. The first is to liberate the children of men from the darkness of ignorance, and guide them to the light of true understanding. The second is to ensure the peace and tranquillity of mankind, and provide all the means by which they can be established.
(Baha’u’llah: Gleanings, pp. 79-80)

The purpose underlying the revelation of every heavenly Book, nay, of every divinely-revealed verse, is to endue all men with righteousness and understanding, so that peace and tranquillity may be firmly established amongst them.
(Baha’u’llah: Gleanings, p. 206)

Guidelines for Establishment:
The Great Being, wishing to reveal the prerequisites of the peace and tranquillity of the world and the advancement of its peoples, hath written: The time must come when the imperative necessity for the holding of a vast, an all-embracing assemblage of men will be universally realized. The rulers and kings of the earth must needs attend it, and, participating in its deliberations, must consider such ways and means as will lay the foundations of the world’s Great Peace amongst men. Such a peace demandeth that the Great Powers should resolve, for the sake of the tranquillity of the peoples of the earth, to be fully reconciled among themselves. Should any king take up arms against another, all should unitedly arise and prevent him. If this be done, the nations of the world will no longer require any armaments, except for the purpose of preserving the security of their realms and of maintaining internal order within their territories. This will ensure the peace and composure of every people, government and nation.
(Baha’u’llah: Gleanings, p. 249)

We pray God – exalted be His glory – and cherish the hope that He may graciously assist the manifestations of affluence and power and the daysprings of sovereignty and glory, the kings of the earth – may God aid them through His strengthening grace – to establish the Lesser Peace. This, indeed, is the greatest means for insuring the tranquillity of the nations. It is incumbent upon the Sovereigns of the world – may God assist them – unitedly to hold fast unto this Peace, which is the chief instrument for the protection of all mankind. It is Our hope that they will arise to achieve what will be conducive to the well-being of man. It is their duty to convene an all-inclusive assembly, which either they themselves or their ministers will attend, and to enforce whatever measures are required to establish unity and concord amongst men. They must put away the weapons of war, and turn to the instruments of universal reconstruction. Should one king rise up against another, all the other kings must arise to deter him. Arms and armaments will, then, be no more needed beyond that which is necessary to insure the internal security of their respective countries. If they attain unto this all-surpassing blessing, the people of each nation will pursue, with tranquillity and contentment, their own occupations, and the groanings and lamentations of most men would be silenced.
(Baha’u’llah: Epistle to the Son of the Wolf, pp. 30-31)

It is necessary that the nations and governments organize an international tribunal to which all their disputes and differences shall be referred. The decision of that tribunal shall be final. Individual controversy will be adjudged by a local tribunal. International questions will come before the universal tribunal, and so the cause of warfare will be taken away.
(`Abdu’l-Baha: Promulgation of Universal Peace, p. 301)

True civilization will unfurl its banner in the midmost heart of the world whenever a certain number of its distinguished and high-minded sovereigns – the shining exemplars of devotion and determination – shall, for the good and happiness of all mankind, arise, with firm resolve and clear vision, to establish the Cause of Universal Peace. They must make the Cause of Peace the object of general consultation, and seek by every means in their power to establish a Union of the nations of the world. They must conclude a binding treaty and establish a covenant, the provisions of which shall be sound, inviolable and definite. They must proclaim it to all the world and obtain for it the sanction of all the human race. This supreme and noble undertaking – the real source of the peace and well-being of all the world – should be regarded as sacred by all that dwell on earth. All the forces of humanity must be mobilized to ensure the stability and permanence of this Most Great Covenant. In this all-embracing Pact the limits and frontiers of each and every nation should be clearly fixed, the principles underlying the relations of governments towards one another definitely laid down, and all international agreements and obligations ascertained. In like manner, the size of the armaments of every government should be strictly limited, for if the preparations for war and the military forces of any nation should be allowed to increase, they will arouse the suspicion of others. The fundamental principle underlying this solemn Pact should be so fixed that if any government later violate any one of its provisions, all the governments on earth should arise to reduce it to utter submission, nay the human race as a whole should resolve, with every power at its disposal, to destroy that government. Should this greatest of all remedies be applied to the sick body of the world, it will assuredly recover from its ills and will remain eternally safe and secure.
(`Abdu’l-Baha: Secret of Divine Civilization, pp. 64-65)

Again, as to religious, racial, national and political bias: all these prejudices strike at the very root of human life; one and all they beget bloodshed, and the ruination of the world. So long as these prejudices survive, there will be continuous and fearsome wars.
To remedy this condition there must be universal peace. To bring this about, a Supreme Tribunal must be established, representative of all governments and peoples; questions both national and international must be referred thereto, and all must carry out the decrees of this Tribunal. Should any government or people disobey, let the whole world arise against that government or people.
(`Abdu’l-Baha: Selections … `Abdu’l-Baha, p. 249)

In short, every means that produces war must be checked and the causes that prevent the occurrence of war be advanced; – so that physical conflict may become an impossibility. On the other hand, every country must be properly delimited, its exact frontiers marked, its national integrity secured, its permanent independence protected, and its vital interests honoured by the family of nations. These services ought to be rendered by an impartial, international Commission. In this manner all causes of friction and differences will be removed. And in case there should arise some disputes between them, they could arbitrate before the Parliament of Man, the representatives of which should be chosen from among the wisest and most judicious men of all the nations of the world.
(`Abdu’l-Baha: Peace, p. 173)

As to the question of disarmament, all nations must disarm at the same time. It will not do at all, and it is not proposed, that some nations shall lay down their arms while others, their neighbours, remain armed. The peace of the world must be brought about by international agreement. All nations must agree to disarm simultaneously…
No nation can follow a peace policy while its neighbour remains warlike. There is no justice in that. Nobody would dream of suggesting that the peace of the world could be brought about by any such line of action. It is to be brought about by a general and comprehensive international agreement, and in no other way…
Simultaneous action, he went on, is necessary in any scheme of disarmament. All the governments of the world must transform their battleships and warcraft into merchant vessels. But no one nation can by itself start in upon such a policy and it would be folly should one power attempt to do so … it would simply invite destruction….
(`Abdu’l-Baha: Peace, p. 171)

O handmaid of God, peace must first be established among individuals, until it leadeth in the end to peace among nations.
(`Abdu’l-Baha: Selections … `Abdu’l-Baha, p. 246)

He [Baha’u’llah] promulgated the adoption of the same course of education for man and woman. Daughters and sons must follow the same curriculum of study, thereby promoting unity of the sexes. When all mankind shall receive the same opportunity of education and the equality of men and women be realized, the foundations of war will be utterly destroyed. Without equality this will be impossible because all differences and distinction are conducive to discord and strife. Equality between men and women is conducive to the abolition of warfare for the reason that women will never be willing to sanction it. Mothers will not give their sons as sacrifices upon the battlefield after twenty years of anxiety and loving devotion in rearing them from infancy, no matter what cause they are called upon to defend. There is no doubt that when women obtain equality of rights, war will entirely cease among mankind.
(`Abdu’l-Baha: Promulgation of Universal Peace, p. 175)

…we do not believe that war is ever necessary and its abolition is one of the essential purposes and brightest promises of Baha’u’llah’s revelation. His specific command to the kings of the earth is: `Should any one among you take up arms against another, rise ye all against him, for this is naught but manifest justice.’ (Tablet to Queen Victoria, `The Proclamation of Baha’u’llah’, p. 13) The beloved Guardian has explained that the unity of mankind implies the establishment of a world commonwealth, a world federal system, `…liberated from the curse of war and its miseries … in which Force is made the servant of Justice…’ whose world executive `backed by an international Force … will safeguard the organic unity of the whole commonwealth.’ This is obviously not war but the maintenance of law and order on a world scale. Warfare is the ultimate tragedy of disunity among nations where no international authority exists powerful enough to restrain them from pursuing their own limited interests.
(The Universal House of Justice: Lights of Guidance, p. 437)

The Future:
Warfare and strife will be uprooted, disagreement and dissension pass away and universal peace unite the nations and peoples of the world. All mankind will dwell together as one family, blend as the waves of one sea, shine as stars of one firmament and appear as fruits of the same tree.
(`Abdu’l-Baha: Promulgation of Universal Peace, p. 145)

Baha’u’llah’s principal mission in appearing at this time in human history is the realization of the oneness of mankind and the establishment of peace among the nations; therefore, all the forces which are focused on accomplishing these ends are influenced by His Revelation. We know, however, that peace will come in stages. First, there will come the Lesser Peace, when the unity of nations will be achieved, then gradually the Most Great Peace – the spiritual as well as social and political unity of mankind, when the Baha’i World Commonwealth, operating in strict accordance with the laws and ordinances of the Most Holy Book of the Baha’i Revelation, will have been established through the efforts of the Baha’is.
(The Universal House of Justice: Lights of Guidance, p. 437)