Nietzsche on modern ethics

In all “science of morals”, so far one thing was lacking, strange as it may sound: the problem of morality itself; what was lacking was any suspicion that there was something problematic here. What the philosophers called “a rational foundation for morality” and tried to supply was, seen in the right light, merely a scholarly variation of the common faith in the prevalent morality; a new means of expression for this faith; and thus just another fact within a particular morality; indeed, in the last analysis a kind of denial that this morality might ever be considered problematic – certainly the very opposite of an examination, analysis, questioning, and vivisection of this very faith.
Beyond Good & Evil, 186

Nietzsche is spot-on here. Most modern attempts to provide a basis for morality that is not grounded on any sort of religion or teleology come out sounding deeply confused. They have, as Nietzsche points out, an after-the-fact feel to them. What they are attempting to do is come up with a grounding for the basic ethical standards everyone assumes to be true. The problem is, in the West moral sentiment is grounded in Christianity. Taking away that grounding while leaving the morality intact is a tall order – one that Nietzsche saw to be impossible. To the question “why ought I be moral”, the modern answer is little more than “just because”. Nietzsche is right to call foul at this.