“Faith is, at one and the same time, absolutely necessary and altogether impossible.”

Decisions Determine Destiny, fireside address http://speeches.byu.edu/reader/reader.php?id=10726| delivered on 6 November 2005.

Source: The Outline of History (1920), Ch. 40

Variant: For those with faith, no evidence is necessary; for those without it, no evidence will suffice.

Section 13; often the final portion of this is quoted alone as: "Absolute faith corrupts as absolutely as absolute power."
Reflections on the Human Condition (1973)
Context: The Savior who wants to turn men into angels is as much a hater of human nature as the totalitarian despot who wants to turn them into puppets.
There are similarities between absolute power and absolute faith: a demand for absolute obedience; a readiness to attempt the impossible; a bias for simple solutions — to cut the knot rather than unravel it; the viewing of compromise as surrender; the tendency to manipulate people and "experiment with blood."
Both absolute power and absolute faith are instruments of dehumanization. Hence absolute faith corrupts as absolutely as absolute power.

Source: The History of Sexuality, Volume 2: The Use of Pleasure

Works of John Dryden (1803) as quoted by P. Fleury Mottelay in William Gilbert of Colchester (1893)
Context: It is almost impossible to translate verbally and well at the same time; for the Latin (a most severe and compendious language) often expresses that in one word which either the barbarity or the narrowness of modern tongues cannot supply in more.... But since every language is so full of its own proprieties that what is beautiful in one is often barbarous, nay, sometimes nonsense, in another, it would be unreasonable to limit a translator to the narrow compass of his author's words; it is enough if he choose out some expression which does not vitiate the sense.

"Stranger in the Village," Harper's (October 1953); republished in Notes of a Native Son (1955)

The Ecological Vision: Reflections on the American Condition (1993)
1990s and later