I do not fail to understand it at all because there is nothing in your argument to understand. Humanistic Law is based on humane morality. Quibbling about a word only draws away from the theme of the argument. Morality, or ethics if you so wish, are the basis, the foundation if you will, of our modern day societal structure. Our form of democracy has shown to be successful, so successful that other countries such as Israel are thinking about adopting it wholeheartedly. This is because our laws are based on the humanistic approach and therefore are ethical, moral, and just.
Divine law need not be just. It just needs faith.