We have no control over God so we cannot make the choice to leave him or to include him in anythings. It is his will that determines the results of our wars or any other activities we engage in. What we must do is find out his will by studying the Bible and then cooperate with him by praying and obeying him.
That sounds like a good idea. The problem is that all of us want war at some level. James 1:1,2 says, "What causes quarrels and what causes fights among you? Is it not this, that your passions are at war within you? You desire and do not have, so you murder. You covet and cannot obtain, so you fight and quarrel." When people achieve political power they have the ability to express these evil desires in war, but the seed of war exists in all of us.