"The divine Prophets are as the coming of spring, each renewing and quickening the teachings of the Prophet Who came before Him."

"Religions are many, but the reality of religion is one. The days are many, but the sun is one. The fountains are many, but the fountainhead is one. The branches are many, but the tree is one.

The foundation of the divine religions is reality; were there no reality, there would be no religions. Abraham heralded reality. Moses promulgated reality. Christ established reality. Muḥammad was the Messenger of reality. The Báb was the door of reality. Bahá’u’lláh was the splendor of reality. Reality is one; it does not admit multiplicity or division. Reality is as the sun, which shines forth from different dawning points; it is as the light, which has illumined many lanterns.

Therefore, if the religions investigate reality and seek the essential truth of their own foundations, they will agree and no difference will be found. But inasmuch as religions are submerged in dogmatic imitations, forsaking the original foundations, and as imitations differ widely, therefore, the religions are divergent and antagonistic. These imitations may be likened to clouds which obscure the sunrise; but reality is the sun. If the clouds disperse, the Sun of Reality shines upon all, and no difference of vision will exist. The religions will then agree, for fundamentally they are the same. The subject is one, but predicates are many.

The divine religions are like the progression of the seasons of the year. When the earth becomes dead and desolate and because of frost and cold no trace of vanished spring remains, the springtime dawns again and clothes everything with a new garment of life. The meadows become fresh and green, the trees are adorned with verdure and fruits appear upon them. Then the winter comes again, and all the traces of spring disappear. This is the continuous cycle of the seasons—spring, winter, then the return of spring. But though the calendar changes and the years move forward, each springtime that comes is the return of the springtime that has gone; this spring is the renewal of the former spring. Springtime is springtime, no matter when or how often it comes. The divine Prophets are as the coming of spring, each renewing and quickening the teachings of the Prophet Who came before Him. Just as all seasons of spring are essentially one as to newness of life, vernal showers and beauty, so the essence of the mission and accomplishment of all the Prophets is one and the same. Now the people of religion have lost sight of the essential reality of the spiritual springtime. They have held tenaciously to ancestral forms and imitations, and because of this there is variance, strife and altercation among them. Therefore, we must now abandon these imitations and seek the foundation of the divine teachings; and inasmuch as the foundation is one reality, the divergent religionists must agree in it so that love and unity will be established among all people and denominations."

`Abdu'l-Bahá, The Promulgation of Universal Peace, pp.126-127 

19 May 1912 
(excerpt from) Talk at Church of the Divine Paternity 
Central Park West, New York