This moral theology has the advantage over speculative theology in that it inevitably leads to the concept of a sole, all-perfect, and rational primordial being. If we consider what the cause must be which gives the necessary law of moral unity its appropriate effect, we conclude that there must be one sole supreme will, which comprehends all these laws in itself. These laws have led us, in virtue of their inner practical necessity, to the postulate of a self-sufficient cause. Practical reason has not attained to the immediate knowledge of God and cannot deduce from the idea of God the moral laws themselves. We cannot look at actions as obligatory because they are the commands of God, we regard them as divine commands because we have an inward obligation to them.
Moral theology is thus of immanent use only.