Selective breeding predates Christianity by at least 10,000 years and Darwin by at least 12,000 years. For instance, all dogs are the result of selective breeding, as the original "dogs" were wolves. Not to mention all the various farm animals long since "domesticated" i.e. selectively bred from their wild ancestors. Darwin didn't discover breeding. Humans were well used to doing that since before recorded history. Darwin merely establish the mechanism by which nature itself did selective breeding without the intervention of the human hand.
The idea --- not invented, but highlighted and made more prominent by Darwin and his successors --- that the human race itself is a product of a process of competition resulting in selection on the one hand, and salutary extinctions on the other, gave fresh inspiration to social Darwinists like Herbert Spencer and Darwin's cousin Sir Francis Galton. Darwin's writings are also prominently cited by racial superiority advocates and eugenicists like Sydney and Beatrice Webb, Bertrand Russell, Oliver Wendell Holmes and Adolf Hitler.
Although he is not responsible for exaggerations and misapplications by his soi-disant disciples, Right and Left, Darwin had persuasive ideas about racial progress; and ideas have consequences.