“[in response to a question about what was meant by his "cosmic religion"] It is not a religion that teaches that man is made in the image of God—that is anthropomorphic. Man has infinite dimensions and finds God in his conscience. This religion has no dogma other than teaching man that the universe is rational and that his highest destiny is to ponder it and co-create with its laws. There are only two limiting factors: first, that what seems impenetrable to us is as important as what is cut and dried; and, second, that our faculties are dull and can only comprehend wisdom and serene beauty in crude forms, but the heart of man through intuition leads us to greater understanding of ourselves and the universe. My religion is based on Moses: Love God and love your neighbor as yourself. And for me God is the First Cause. David and the prophets knew that there could be no love without justice or justice without love. I don't need any other religious trappings.”

Variant translation: Though it is very important for man as an individual that his religion should be true, that is not the case for society. Society has nothing to fear or hope from another life; what is most important for it is not that all citizens profess the true religion but that they should profess religion.
Source: Democracy in America, Volume I (1835), Chapter XV-IXX, Chapter XVII.

Fragments of Markham's notes
The Nemesis of Faith (1849)
Context: A man is born into the world — a real man — such a one as it has never seen; he lives a life consistently the very highest; his wisdom is the calm earnest voice of humanity; to the worldly and the commonplace so exasperating, as forcing upon them their own worthlessness — to the good so admirable that every other faculty is absorbed in wonder. The one killed him. The other said, this is too good to be a man — this is God. His calm and simple life was not startling enough for their eager imagination; acts of mercy and kindness were not enough, unless they were beyond the power of man. To cure by ordinary means the bruised body, to lift again with deep sympathy of heart the sinking sinner was not enough. He must speak with power to matter as well as mind; eject diseases and eject devils with command. The means of ordinary birth, to the oriental conception of uncleanness, were too impure for such as he, and one so holy could never dissolve in the vulgar corruption of the grave.
Yet to save his example, to give reality to his sufferings, he was a man nevertheless. In him, as philosophy came in to incorporate the first imagination, was the fulness of humanity as well as the fulness of the Godhead. And out of this strange mixture they composed a being whose life is without instruction, whose example is still nothing, whose trial is but a helpless perplexity. The noble image of the man is effaced, is destroyed. Instead of a man to love and to follow, we have a man-god to worship. From being the example of devotion, he is its object; the religion of Christ ended with his life, and left us instead but the Christian religion.

Dissertation for doctor of philosophy in christian education (May 25, 1991)

As quoted in Leaping Souls : Rabbi Menachem Mendel And The Spirit Of Kotzk (1993) by Chaim Feinberg
Variant translation: Man must "guard himself and his uniqueness, and not imitate his fellow … for initially man was created in his own image, and only afterwards in the image of God.

Source: Going Home: Jesus and Buddha as Brothers

§ I
1910s, At the Feet of the Master (1911)
Context: In all the world there are only two kinds of people — those who know, and those who do not know; and this knowledge is the thing which matters. What religion a man holds, to what race he belongs — these things are not important; the really important thing is this knowledge — the knowledge of God's plan for men. For God has a plan, and that plan is evolution. When once a man has seen that and really knows it, he cannot help working for it and making himself one with it, because it is so glorious, so beautiful. So, because he knows, he is on God's side, standing for good and resisting evil, working for evolution and not for selfishness.
If he is on God's side he is one of us, and it does not matter in the least whether he calls himself a Hindu or a Buddhist, a Christian or a Muhammadan, whether he is an Indian or an Englishman, a Chinaman or a Russian. Those who are on His side know why they are here and what they should do, and they are trying to do it; all the others do not yet know what they should do, and so they often act foolishly, and try to invent ways for themselves which they think will be pleasant for themselves, not understanding that all are one, and that therefore only what the One wills can ever be really pleasant for any one. They are following the unreal instead of the real. Until they learn to distinguish between these two, they have not ranged themselves on God's side, and so this discrimination is the first step.
But even when the choice is made, you must still remember that of the real and the unreal there are many varieties; and discrimination must still be made between the right and the wrong, the important and the unimportant, the useful and the useless, the true and the false, the selfish and the unselfish.

Complete Works of Swami Vivekananda, Calcutta, 1985, Volume VI, p. 85. Quoted from Goel, S. R. (1996). History of Hindu-Christian encounters, AD 304 to 1996. Chapter 13 ISBN 9788185990354

Tu Fu: Poems (p. 91)
Classics Revisited (1968)

Misattributed
Variant: The religion of the future will be a cosmic religion. It should transcend a personal God and avoid dogmas and theology. Covering both the natural and the spiritual, it should be based on a religious sense arising from the experience of all things, natural and spiritual as a meaningful unity. If there is any religion that would cope with modern scientific needs, it would be Buddhism.
These two statements are very similar, widely quoted, and seem to paraphrase some ideas in the essay "Religion and Science" (see below), but neither of the two specific quotes above been properly sourced. Notable Einstein scholars such as John Stachel and Thomas J. McFarlane (author of Buddha and Einstein: The Parallel Sayings) know of this statement but have not found any source for it. Any information on any definite original sources for these is welcome.
This quote does not actually appear in Albert Einstein: The Human Side as is sometimes claimed.
Only two sources from before 1970 can be found on Google Books. The first is The Theosophist: Volume 86 which seems to cover the years 1964 http://books.google.com/books?id=7pLjAAAAMAAJ&q=1964#search_anchor and 1965 http://books.google.com/books?id=7pLjAAAAMAAJ&q=1965#search_anchor. The quote appears attributed to Einstein on p. 255 http://books.google.com/books?id=7pLjAAAAMAAJ&q=%22natural+and+spiritual%22#search_anchor, with the wording given as "The religion of the future will be a cosmic religion. It should transcend a personal God and avoid dogmas and theology. Covering both the natural and the spiritual, it should be based on a religious sense arising from the experience of all things, natural and spiritual, as a meaningful unity. Buddhism answers this description." An identical quote appears on p. 284 http://books.google.com/books?id=YpsfAQAAIAAJ&q=%22dogmas+and+theology%22#search_anchor of The Maha Bodhi: Volume 72 published by the Maha Bodhi Society of India, which seems to contain issues from throughout 1964 http://books.google.com/books?id=YpsfAQAAIAAJ&q=%22volume+72%22#search_anchor.
A number of phrases in the quote are similar to phrases in Einstein's "Religion and Science". Comparing the version of the quote in The Theosophist to the version of "Religion and Science" published in 1930, "a cosmic religion" in the first resembles "the cosmic religious sense" in the second; "transcend a personal God" resembles "does not involve an anthropomorphic idea of God"; "covering both the natural and the spiritual" resembles "revealed in nature and in the world of thought"; "the experience of all things, natural and spiritual, as a meaningful unity" resembles "experience the totality of existence as a unity full of significance"; and "Buddhism answers this description" resembles "The cosmic element is much stronger in Buddhism". These phrases appear in the same order in both cases, and the ones from "Religion and Science" are all from a single paragraph of the essay.
Context: Buddhism has the characteristics of what would be expected in a cosmic religion for the future: It transcends a personal God, avoids dogmas and theology; it covers both the natural and the spiritual, and it is based on a religious sense aspiring from the experience of all things, natural and spiritual, as a meaningful unity.