"All these holy, divine Manifestations are one."

"The divine Manifestations since the day of Adam have striven to unite humanity so that all may be accounted as one soul. The function and purpose of a shepherd is to gather and not disperse his flock. The Prophets of God have been divine Shepherds of humanity. They have established a bond of love and unity among mankind, made scattered peoples one nation and wandering tribes a mighty kingdom. They have laid the foundation of the oneness of God and summoned all to universal peace. All these holy, divine Manifestations are one. They have served one God, promulgated the same truth, founded the same institutions and reflected the same light. Their appearances have been successive and correlated; each One has announced and extolled the One Who was to follow, and all laid the foundation of reality. They summoned and invited the people to love and made the human world a mirror of the Word of God. Therefore, the divine religions They established have one foundation; Their teachings, proofs and evidences are one; in name and form They differ, but in reality They agree and are the same. These holy Manifestations have been as the coming of springtime in the world. Although the springtime of this year is designated by another name according to the changing calendar, yet as regards its life and quickening it is the same as the springtime of last year. For each spring is the time of a new creation, the effects, bestowals, perfections and life-giving forces of which are the same as those of the former vernal seasons, although the names are many and various. This is 1912, last year was 1911 and so on, but in fundamental reality no difference is apparent. The sun is one, but the dawning points of the sun are numerous and changing. The ocean is one body of water, but different parts of it have particular designations—Atlantic, Pacific, Mediterranean, Antarctic, etc. If we consider the names, there is differentiation; but the water, the ocean itself, is one reality."

`Abdu'l-Bahá, The Promulgation of Universal Peace, p. 151 

28 May 1912
(excerpt from) Talk at Reception at Metropolitan Temple
Seventh Avenue and Fourteenth Street, New York