"The underlying foundation of the religions is one; there is no intrinsic difference between them."

"The body politic may be likened to the human organism. As long as the various members and parts of that organism are coordinated and cooperating in harmony, we have as a result the expression of life in its fullest degree. When these members lack coordination and harmony, we have the reverse, which in the human organism is disease, dissolution, death. Similarly, in the body politic of humanity dissension, discord and warfare are always destructive and inevitably fatal. All created beings are dependent upon peace and coordination, for every contingent and phenomenal being is a composition of distinct elements. As long as there is affinity and cohesion among these constituent elements, strength and life are manifest; but when dissension and repulsion arise among them, disintegration follows. This is proof that peace and amity, which God has willed for His children, are the saving factors of human society, whereas war and strife, which violate His ordinances, are the cause of death and destruction. Therefore, God has sent His Prophets to announce the message of goodwill, peace and life to the world of mankind.

Inasmuch as the essential reality of the religions is one and their seeming variance and plurality is adherence to forms and imitations which have arisen, it is evident that these causes of difference and divergence must be abandoned in order that the underlying reality may unite mankind in its enlightenment and upbuilding. All who hold fast to the one reality will be in agreement and unity. Then shall the religions summon people to the oneness of the world of humanity and to universal justice; then will they proclaim equality of rights and exhort men to virtue and to faith in the loving mercy of God. The underlying foundation of the religions is one; there is no intrinsic difference between them. Therefore, if the essential and fundamental ordinances of the religions be observed, peace and unity will dawn, and all the differences of sects and denominations will disappear."

`Abdu'l-Bahá, The Promulgation of Universal Peace, pp. 98-99

5 May 1912 
(excerpt from) Talk at All-Souls Church 
Lincoln Center, Chicago, Illinois