Transvaluation of all values
Elaborating the concept in The Antichrist, Nietzsche asserts that Christianity, not merely as a religion but also as the predominant moral system of the Western world, in fact inverts nature, and is "hostile to life". As "the religion of pity", Christianity elevates the weak over the strong, exalting that which is "ill-constituted and weak" at the expense of that which is full of life and vitality.
Christianity is contrasted unfavorably, for example, with Buddhism. Nietzsche posits that while Christianity is "the struggle against sin", Buddhism is "the struggle against suffering"; to Nietzsche, Christianity limits and lowers humankind by assailing its natural and inevitable instincts as depraved ("sin"), whereas Buddhism advises one merely to eschew suffering. While Christianity is full of "revengefulness" and "antipathy" (e.g., the Last Judgment), Buddhism promotes "benevolence, being kind, as health-promoting." Buddhism is also suggested to be the "honest" of the two religions, for its being strictly "phenomenalistic", and because "Christianity makes a thousand promises but keeps none." Martyrdom, rather than being a moral high ground or position of strength, is indicative of an "obtuseness to the question of truth."
Similarly, Nietzsche contrasts 19th-century European morality to that of pre-Christian Greek civilization. Because sex is, in Nietzsche's thought, a very fundamental affirmation of life, for its being the very process by which human life is created, Christianity's elevation of chastity (including, for example, the story of Mary's virginal pregnancy) is counter to the natural instincts of humanity, and therefore a contradiction of "natural values".
Nietzsche's enthusiasm for what he called "the transvaluation of all values" stemmed from a contempt for Christianity and the entirety of the moral system that flowed from it: indeed, "contempt of man", as Nietzsche states near the end of The Antichrist. Nietzsche perceived the moral framework of Christian civilization to be oppressive: reproduction derided as sinful, and life as a mere investment toward the hollow promise of an illustrious afterlife: death prevailing over life. The transvaluation of all values would mean the exaltation of life rather than the exaltation of suffering, and an acceptance of every instinct or lust as organic and therefore valid, therefore beyond the scope of moral condemnation. What one desires would merely be what one desires, rather than either sinful or pious. What one desires would be the product of stimuli rather than the product of "will".
I call Christianity the one great curse, the one great intrinsic depravity, the one great instinct for revenge for which no expedient is sufficiently poisonous, secret, subterranean, petty -- I call it the one immortal blemish of mankind…
And one calculates time from the dies nefastus on which this fatality arose -- from the first day of Christianity! Why not rather from its last? From today? Revaluation of all values!
—Nietzsche, Conclusion, The Antichrist.
The Revaluation of All Values was also the working title of a series of four books Nietzsche was planning to write, only the first of which – The Antichrist – he completed. However, one of his schemes for The Will to Power used "The Revaluation of All Values" as a subtitle, and it was this scheme that his sister Elisabeth Förster-Nietzsche used to assemble his notes into the final book with that title.