Morality is the adjustment of matter to its environment—the natural arrangement of molecules. More especially it may be considered as dealing with organic molecules. Conventionally it is the science of reconciling the animal Homo (more or less) sapiens to the forces and conditions with which he is surrounded. It is linked with religion only so far as the natural elements it deals with are deified and personified. Morality antedated the Christian religion, and has many times risen superior to coexistent religions. It has powerful support from very non-religious human impulses. Personally, I am intensely moral and intensely irreligious. My morality can be traced to two distinct sources, scientific and aesthetic. My love of truth is outraged by the flagrant disturbance of sociological relations involved in so-called wrong; whilst my aesthetic sense is outraged and disgusted with the violations of taste and harmony thereupon attendant. But to me the question presents no ground for connexion with the grovelling instinct of religion. However—you may exclude me from the argument, if you will. I am unduly secluded though unavoidably so. We will deal only with materials that may presumably lie within my feeble reach. Only one more touch of ego. I am not at all passive or indifferent in my zeal for a high morality. But I cannot consider morality the essence of religion, as you seem to. In discussing religion, the whole fabric must bear examination before the uses or purposes are considered. We must investigate the cause as well as alleged effects if we are to define the relation between the two, and the reality of the former. And more, granting that the phenomenon of faith is indeed the true cause of the observed moral effects; the absolute basis of that phenomenon remains to be examined. The issue between theists and atheists is certainly not, as you seem to think, the mere question of whether religion is useful or detrimental.
— From H.P. Lovecraft’s 1918 letter to his friend Maurice W. Moe; the letter is collected in The Portable Atheist (ed. Christopher Hitchens).