“God is one, but He is worshipped in different ages and climes under different names and aspects.”

Statement of 1938, as quoted in Meher Baba On War : And Other Relevant Messages (1972); also Discourses (1987), p. 268<!-- 1938, India, MJ 1:1 p 4-7 -->
General sources
Context: The Avatar appears in different forms, under different names, at different times, in different parts of the world. As his appearance always coincides with the spiritual birth of man, so the period immediately preceding his manifestation is always one in which humanity suffers from the pangs of the approaching birth.

Source: The Lonesome Gods (1983), Ch. 8
Context: Long ago, before the Indians who live here now, there were other people.  Perhaps they went away, or maybe they died or were driven out by these Indians’ ancestors, but they are gone. Yet sometimes I am not sure they are gone. I think sometimes their spirits are still around, in the land they loved.
Each people has its gods, or the spirits in which they believe. It may be their god is the same as ours, only clothed in different stories, different ideas, but a god can only be strong, Hannes, if he is worshiped, and the gods of those ancient people are lonesome gods now.
They are out there in the desert and mountains, and perhaps their strength has waned because nobody lights fires on their altars anymore. But they are there, Hannes, and sometimes I think they know me and remember me.

C. Rajagopalachari (1900) Hinduism, doctrine and way of life https://archive.org/stream/cu31924091600688#page/n37/mode/2up, p. 31; As quoted in [Rao, K.L. Seshagiri, Mahatma Gandhi And Comparative Religion, http://books.google.com/books?id=HSGWZ9mpNl4C&pg=PA110, 1 January 1990, Motilal Banarsidass Publ., 978-81-208-0767-9, 110–]

Explaining why he used many different pseudonyms.
Oxford Companion to Children's Literature: "Charles Hamilton" (pages 235-7)

Letter to the Reverend Ensor Walters (1933), as quoted in Bernard Shaw : Collected Letters, 1926-1950 (1988) by Dan H. Laurence, p. 305; Shaw actually errs here in characterizing Jainism as simply a sect of Hinduism, as it is usually regarded as a separate and independent tradition, though Hindu and Jain philosophers have long had influence on each other, as well as other traditions
1940s and later
Context: The apparent multiplicity of Gods is bewildering at the first glance; but you presently discover that they are all the same one God in different aspects and functions and even sexes. There is always one uttermost God who defies personification. This makes Hinduism the most tolerant religion in the world, because its one transcendent God includes all possible Gods… Hinduism is so elastic and so subtle that the profoundest Methodist and the crudest idolater are equally at home in it.
Islam is very different, being ferociously intolerant. What I may call Manifold Monotheism becomes in the minds of very simple folk an absurdly polytheistic idolatry, just as European peasants not only worship Saints and the Virgin as Gods, but will fight fanatically for their faith in the ugly little black doll who is the Virgin of their own Church against the black doll of the next village. When the Arabs had run this sort of idolatry to such extremes … they did this without black dolls and worshipped any stone that looked funny, Mahomet rose up at the risk of his life and insulted the stones shockingly, declaring that there is only one God, Allah, the glorious, the great… And there was to be no nonsense about toleration. You accepted Allah or you had your throat cut by someone who did accept him, and who went to Paradise for having sent you to Hell. Mahomet was a great Protestant religious force, like George Fox or Wesley….
There is actually a great Hindu sect, the Jains, with Temples of amazing magnificence, which abolish God, not on materialist atheist considerations, but as unspeakable and unknowable, transcending all human comprehension.

Last Notebook (1942) p. 308
First and Last Notebooks (1970)
Context: No human being escapes the necessity of conceiving some good outside himself towards which his thought turns in a movement of desire, supplication, and hope. consequently, the only choice is between worshipping the true God or an idol. Every atheist is an idolater — unless he is worshipping the true God in his impersonal aspect. The majority of the pious are idolaters.

Review of Power: A New Social Analysis by Bertrand Russell in The Adelphi (January 1939); Paraphrased variant: Sometimes the first duty of intelligent men is the restatement of the obvious.
Context: If there are certain pages of Mr Bertrand Russell's book, Power, which seem rather empty, that is merely to say that we have now sunk to a depth at which the restatement of the obvious is the first duty of intelligent men. It is not merely that at present the rule of naked force obtains almost everywhere. Probably that has always been the case. Where this age differs from those immediately preceding it is that a liberal intelligentsia is lacking. Bully-worship, under various disguises, has become a universal religion, and such truisms as that a machine-gun is still a machine-gun even when a "good" man is squeezing the trigger — and that in effect is what Mr Russell is saying — have turned into heresies which it is actually becoming dangerous to utter.

Source: The Gospel of Sri Ramakrishna (1942), p. 423
Context: Truth is one; only It is called by different names. All people are seeking the same Truth; the variance is due to climate, temperament, and name. A lake has many ghats. From one ghat the Hindus take water in jars and call it "jal". From another ghat the Mussalmāns take water in leather bags and call it "pāni". From a third the Christians take the same thing and call it "water". Suppose someone says that the thing is not "jal" but "pāni", or that it is not "pāni" but "water", or that it is not "water" but "jal", It would indeed be ridiculous. But this very thing is at the root of the friction among sects, their misunderstandings and quarrels. This is why people injure and kill one another, and shed blood, in the name of religion. But this is not good. Everyone is going toward God. They will all realize Him if they have sincerity and longing of heart.

Volume I, Book I http://books.google.com/books?id=US0bhPS4h2UC&pg=PA79
The World as Will and Representation (1819; 1844; 1859)