What has Christianity truly contributed to humanity

[Angrboda]

Even if it did, the Christian establishment of the past centuries wasn't very good at implementing those concepts.  It took the Enlightenment and, to borrow a term from Karl Popper, piecemeal social engineering, to make any inroads.

Your point is well taken. The gap beyween theory and practice persisted for centuries. That said, the Enlightenment did not provide substitute a rational substitute for the religious claim of existential equality; it simply took the Christian ideal for granted, much the way secularists still do. Before Judeo-Christian ideas took hold, the notion of human dignity simply did not exist in pagan cultures. The weak and poor were universally held in contempt. The very notion of a cruxified savior was inconcievable. Nietzsche astutely characterized it as "slave morality" from a classical perspective. The sermon on the mound has no parallel in the West., IDK about other parts of the ancient world.

Christianity has historically been a case of "all animals are equal, yet some are more equal than others." Treating the Jews as less than human was institutionalized by Christianity. And treating blacks as less than fully human persisted long after the end of slavery with the bastion of Christianity in the southern United States continuing to treat blacks that way long into the 20th century. It has been secularism with its emphasis on fairness and inclusivity that has righted the ship of Christian morals. Karen Armstrong in her book on the Axial Age makes the argument that multiple cultures across the globe gave birth to religious philosophies that emphasized compassion and self-renewal, it was just a matter that Christianity won out due to the European advantages cataloged by Jared Diamond in his book, Guns, Germs, and Steel. Christianity didn't win out by being better on human rights, it wasn't -- other religions hold that crown -- it won out because of a favorable cast of the die. Nothing about Christianity's claimed moral contributions holds up to scrutiny.