They come from reality.
Moral absolutes just are....Since you just keep repeating this, you obviously believe they are real, however, you don't know their source (otherwise you would have named it). How odd... Evidently, you are taking it "on blind faith" that moral absolutes are real - but you don't know where they are from, you just KNOW they aren't from God! You are so bent on denying that God is the source, you are satisfied to say they just are... It seems you have your moral feet planted in mid-air. I think you have some serious thinkin to do...