What separates me from most atheists is a feeling of utter humility toward the unattainable secrets of the harmony of the cosmos. The fanatical atheists are like the slaves who are still feeling the weight of their chains which they have thrown off after hard struggle. They are creatures who — in their grudge against traditional religion as the “opium of the masses” — cannot hear the music of the spheres. I prefer the attitude of humility corresponding to the weakness of our intellectual understanding of nature and our own being. Science without religion is lame, religion without science is blind.

Albert Einstein (1879-1955) German-American physicist
(Spurious / Synthetic)

This quotation is actually a synthesis of several Einstein quotes. It is sometimes attributed as a whole to "Science, Philosophy and Religion, A Symposium" (1941), but only a part is found there. Nor is it found at all  in the also sometimes cited "Religion and Science," New York Times Magazine (9 Nov 1930)

The "utter humility" portion is attributed as a letter from Einstein to Joseph Lewis (18 Apr 1953).  It was quoted in Walter Isaacson, Einstein (2007). The “fanatical” through “spheres” portion is in a letter (7 Aug 1941) discussing responses to his essay “Science and Religion” (1941) per Max Jammer, Einstein and Religion: Physics and Theology (1999)

The “weakness of our intellectual understanding” phrase is attributed to a letter to Guy H. Raner Jr. (28 Sep 1949), quoted in the Isaacson work as well as by Michael R. Gilmore in Skeptic, Vol. 5, No. 2.

The lame/blind phrase is attributed to a letter to Eric Gutkind (3 Jan 1954). It was earlier used by Einstein (1941) at the Symposium cited above.

This synthetic quotation is a good example of the difficulties in quoting Einstein, who is used as a polemical bludgeon by a variety of groups, and is often poorly or incorrectly cited online, compounded by his re-use the same turns of phrase multiple times in his correspondence and papers.