Just like different parts of an ocean have particular designations such as Atlantic, Pacific, etc., so it is with respect to various religions -- their reality is one.

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. Likewise, the divine religions of the holy Manifestations of God are in reality one, though in name and nomenclature they differ. (‘Abdu’l-Baha, excerpt from a talk, 28 May 1912, New York; ‘The Promulgation of Universal Peace’) (To read the entire talks please visit Talks of 'Abdu'l-Baha)