All men are made in the image of God;
God, as everybody knows, is not a Negro;
Therefore the Negro is not a man.
I'm not sure if he meant this mostly seriously or mostly in jest. But the reality is that some people actually felt that way. Charles Carroll, for instance, wrote in The Negro a Beast:
The Bible plainly teaches that man was created a single pair, "in the image of God." And we feel assured that a careful consideration of this subject must lead any rational mind to decide that the White, with his exalted physical and mental characters, and the Negro with his ape-like physical and mental characters, are not the progeny of one primitive pair. This is admitted by the great thinkers of the earth. Mr. Haeckel says: "The excellent paleontologist Quenstedt is right in maintaining that, "it Negroes and Caucasians were snails, zoologists would universally agree that they represented two very distinct species, which could never have originated from one pair by gradual divergence.—History of Creation.
This being true, it follows that, if the White was created "in the image of God," then the Negro was made after some other model. And a glance at the Negro indicates the model; his very appearance suggests the ape.
This arbitrary decision wasn't limited to African Americans, though. Oliver Wendell Holmes delivered a speech in 1855 where he said,
The question of interfering races is a very terrible one; it never was, and perhaps never will be, settled according to the abstract principles of justice. Look at the aboriginal inhabitants of the land we occupy. It pleased the Creator to call into existence this half-filled outline of humanity; this sketch in red crayons of a rudimental manhood; to keep the continent from being a blank until the true lord of creation should come to claim it. Civilization and Christianity have tried to humanize him, and he proves a dead failure. Theologians stand aghast at a whole race destined, according to their old formulæ, to destruction, temporal and eternal. Philanthropists mourn over them, and from time to time catch a red man and turn him into their colleges as they would turn a partridge in among the barn-door fowls. But instinct has its way sooner or later; the partridge makes but a troublesome chicken, and the Indian but a sorry Master of Arts, if he does not run for the woods, where all the feræ naturæ impulses are urging him. These instincts lead to his extermination; too often the sad solution of the problem of his relation to the white race. As soon as any conflict arises between them, his savage nature begins to show itself. He dashes the babes' heads against their fathers' hearthstones--as at our Oxford--a heap of stones still shows you where he did it; or flings them out of windows, as at Haverhill; he mutilates his prostrate enemy; he drives away the women like beasts of burden. Then the white man hates him, and hunts him down like the wild beasts of the forest, and so the red-crayon sketch is rubbed out, and the canvas is ready for a picture of manhood a little more like God's own image.
Native Americans were not real men. Everyone knows that white men were the only ones made in the image of god--god himself was white! When he wasn't a burning bush. Or a pillar of smoke. Or, uh, whatever.