The idea that Christian ethics is a ressentiment ethics is a Nietzschean conception. Max Scheler says much the same when he notes that Christianity is defended by certain believers as if taking vengeance on antiquity, combating the evil that prevailed before Christianity came into being and challenged that power (Scheler 48).
The term "ressentiment" has been made into a technical term by Nietzsche, but it is first of all the French word for "resentment," though as Manfred S. Frings notes, the French word possesses a sense of lingering hatred that the English word does not. Nietzsche expropriated the French term because the German language does not have a word for "ressentiment" (Frings 5).
In the opening chapter of On the Genealogy of Morals, Friedrich Nietzsche examines the history of the central concepts of morality and addresses the development of the concepts of good and evil. He sees good as having developed as the result of ressentiment, or resentment. One of the consequences was the "slave revolt" in the battle between Rome and Judea, a revolt which Nietzsche sees as key in the development of our moral sense in Western society. The references to Rome and Judea are to be taken not only as references to the kingdoms so named but to the dominant power in society and the lesser element, the oppressed, who ultimately prevail. Rome represents the higher type of human being, those who create their own values from their own inner strength and impose those values on others. The meek and powerless have good reason to fear the strong and powerful, and what they come to feel is ressentiment, a resentment of those with power. The mass of humanity comes to assert its own values as a way of protecting the weak from the powerful, and this leads to the revolt of the slaves. Resentment in this sense is a creative force that produces real change and that brings a new and powerful set of values into being.
Nietzsche is pointi...