It's fascinating that Du Bois chooses the words "turned against it." The words lend the sentence a stronger meaning than it might appear on first glance. Du Bois is not saying simply that the United States' racism betrays its ideals and that therefore is not as great as it could be. He is saying that its racism actively hurts it. This is clear when he gets into his discussion of Jim Crow's harms on democracy and the corruption of white America's morality. "Turned against it" doesn't just mean ignored, or tossed to the side. It means, quite literally, "turned against it": used to harm the country instead of to heal it.

I think this passage is really important because a lot of his text seems to be underselling the role that race plays in, well, racism. Du Bois places so much emphasis on the economic causes of racism that one could almost get away with thinking that race is simply incidental to the problem. He reminds us here that although the origins of racism may be economic, its oppression is not limited according to economics; all black people are discriminated against, no matter their economic or educational status. And although racism may harm the white man as much as the black man, it is clearly directed against the black man, for no other reason than the color of his skin.