The ethical argument for the existence of God is as follows. Nothing is intrinsically good except virtue, which consists in doing right without any ulterior motive. Every one can always act virtuously whether God exists or not. But, although virtue is the only intrinsic good, it is not, as we have seen, the complete good. The complete good is composed of virtue with the appropriate amount of happiness. Now we can say of the complete good that it ought to exist. But what ought to be must be possible, and therefore the necessary conditions of its possibility must be actual. Now there is no necessary connexion between virtue and happiness either logically or by way of ordinary natural causation. There is no logical connexion, because virtue cannot be defined in terms of happiness, and there are many other kinds of happiness beside the feeling of satisfaction with one's own virtue. And there is no causal connexion by the ordinary laws of Nature. Virtue depends wholly on oneself, and, on Kant's view, can always be realised no matter how unfavourable the conditions may be. But happiness depends largely on one's innate tastes and dispositions, on the state of one's bodily health, and on external circumstances. And a perfectly virtuous man has no more control over these than a vicious one. The position then is this. The complete good must be capable of existing, since it ought to exist. One of its factors, viz., perfect virtue, is possible under all circumstances. But the other factor, viz., the deserved amount of happiness, will be realised only if the course of Nature be deliberately overruled so as to secure it. And the only way in which we can conceive this happening is by supposing that Nature is dependent on a powerful, benevolent, and moral being, who arranges that in the long run virtue shall be rewarded by the appropriate amount of happiness.
(C. D. Broad, Five Types of Ethical Theory [London and Henley: Routledge & Kegan Paul, 1930], 140-1 [italics in original])
Keith Burgess-Jackson, J.D., Ph.D. 