The pantheists, who believe that God is the soul and the world is the body, must either be wrong or live in a constant state of blasphemy as we trample upon God's 'body' even in the daily use of creation.
Nor should we worship universal reason as god--this is akin to contemporary trends in rationalist scientific thought (as well as certain mystical Eastern streams, at least if my Facebook feed is any indicator). "God" is not the totality of all reason that then works itself out through mankind. This sort of pan-en-theism was very popular both in Augustine's day and in the works of certain heretics of the 19th century (one thinks of Swedenborg and the fringes of German Idealism). Given the pervasive nature of human sin, we certainly cannot say that we are a part of God. Augustine is careful to maintain the creature/Creator distinction.
Jupiter does not even reign over the kingdoms of this earth (let alone everything). If we had to pick a pagan god to attribute such things to, surely it would be "Victory"? After all, it's the victory of a nation in wars that expands the borders. What other god would be necessary?
Theoretically, wars should only happen in a "good" nation with "good" rulers when neighboring nations are unjustly awful and need to be subdued. You can hear Augustine's sarcasm as he suggests that clearly the Romans were lucky to be surrounded by so many unjust figures!
At the end of the day, the only reason for the expansion of a human kingdom is the desire for increasing domination--this is not something which we can say Jupiter provides.
The priorities of the Romans when thinking about the gods are clearly skewed, since they put the temple of "Quiet" outside the gate and inside worship a cacophony of demons in the guise of gods.