What did Nietzsche mean by accusing Christianity of slave-morality?
“I finally discovered two basic types and one basic difference. There
are master morality and slave morality. . . . The moral discrimination
of values has originated either among a ruling group whose
consciousness of its difference from the ruled group was accompanied
by delight - or among the ruled, the slaves and dependents of every
degree.” ... “The Christian faith is from the beginning a sacrifice:
sacrifice of all freedom, all pride, all self-confidence of the
spirit, at the same time enslavement and self-mockery, selfmutilation
… Modern men, with their obtuseness to all Christian nomenclature, no
longer sense the gruesome superlative which lay for an antique taste
in the paradoxical formula ‘god on the cross’. Never and nowhere has
there hitherto been a comparable boldness in inversion, anything so
fearsome, questioning and questionable, as this formula: it promised a
revaluation of all antique values. – It is the orient, the innermost
orient, it is the oriental slave who in this fashion took vengeance on
Rome and its noble and frivolous tolerance, on Roman ‘Catholicism’ of
faith – and it has never been faith but always freedom from faith,
that half-stoical unconcern with the seriousness of faith, that has
enraged slaves in their masters and against their masters.
‘Enlightenment’ enrages: for the slave wants the unconditional, he
understands in the domain of morality too only the tyrannical, he
loves as he hates, without nuance, into the depths of him, to the
point of pain, to the point of sickness – the great hidden suffering
he feels is enraged at the noble taste which seems to deny suffering.”
Nietzsche - Beyond Good and Evil.
“The act of most spiritual revenge. It was the Jews who, with awe
inspiring consistency, dared to invert the aristocratic value-equation
(good = noble = powerful = beautiful = happy = beloved of God) and to
hang onto this inversion with their teeth, the teeth of the most
abysmal hatred (the hatred of impotence), saying, "the wretched alone
are the good; the suffering, deprived, sick, ugly alone are pious,
alone are blessed by God . . . and you, the powerful and noble, are on
the contrary the evil, the cruel, the lustful, the insatiable, the
godless to all eternity, and you shall be in all eternity the
unblessed, the accursed, and damned!"
Nietzsche - Genealogy of Morals
Nietzsche traces the master and slave morality back to the masters and slaves of ancient times. He suggests that our most cherished values originated not among those who were the best and brightest of their times, but among those who were the most oppressed and impoverished. The dominant emotion in the evolution of morality, in other words, was not pride in oneself or one's people, but a defensive prejudice against all of those who succeeded and achieved the happiness that one could not oneself achieve. Nietzsche argues that the roots of ressentiment morality are to be found in the history of the Jews. In ‘Jewish hatred’ for the Roman oppressor lie the seeds of Christian faith and morality. The ancient Hebrews and then the early Christians simmered with resentment and concocted a fabulous philosophical strategy against their ancient masters. Instead of seeing themselves as failures in the competition for wealth and power, they re-valued their values and turned their resentment into self-righteousness. Morality is the product of this self-righteous resentment, which is not nearly so concerned with living the good life as it is with chastizing those who do live it. In its extreme form - asceticism - it is the active denial of the good life, the ultimate outlet of resentment as self-righteous self-denial.
Nietzsche suggests then, on the basis of this analysis, that Christian morality is inherently structured as a form of slave morality's ressentiment toward the masters, and it accomplishes revenge imaginatively, by means of passing judgment. The strong, active traits of the masters are vilified by the slavish, who come to regard their own passivity and weakness as virtues. This pattern pervades the moral ideals of Christianity. Many modes of self-assertion and self-expression are analyzed as sins on the Christian scheme, while passive suffering is deemed characteristic of the blessed. Since Christianity is based on "slave morality' it must be a point of honor for the "strong" to overcome it. For them it is"indecent" to still be Christians. Nietzsche assert with regularity that religion is necessary primarily or solely for the weak.