I cannot overstress the importance of the fact that, once gravity is included in our considerations of nature, one is no longer free to define the total energy of a system arbitrarily, nor the fact that there are both positive and negative contributions to this energy...I say this because it have been argued that the statement that the average total Newtonian gravitational energy in a flat, expanding universe is arbitrary, and that any other balue would be just as good, but that scientists 'define' the zero point to argue against God. So claimed Dinesh D'Souza, anyway, in his debates with Christopher Hitchens on the existence of God.