Whose side is God on?

I stopped on a religious channel where an American soldier was recounting his experiences in Iraq. Several times he explained how he kept asking God to show that He was on his side. It seemed bizarre and incongruent that a believer should call on God while he is directing his tank to bombard the hell out of people across the river.

It made me think of the old expression "Praise the Lord and pass the ammunition". Certainly anyone uttering this phrase sees the irony in it. Was the soldier's tale any different? How different was his situation from the enemy combatants possibly shouting "Allah is great!"?

I can understand a person defending his life with deadly force if he were in immediate danger. I cannot comprehend someone going half way around the world with the express purpose of killing people and then invoking God's name for his protection or even His help in killing other human beings.