Is Christianity Guerilla Warfare?

From a posting I wrote for my Theology Of Evangelism Class

If it is true that we are in a "spiritual battle" and that there is "spiritual warfare" happening all around us...why does the church insist on "standing in open fields and lining up face to face with the enemy" like we did in the revolutionary war.

Why is it that we build bohemoth buildings, set up elephant like heirarchies, and fight the enemy as though he is willing to fight like a normal enemy?

Sin takes root in the shadowy places, in the secret places. In the homes, bars, workplaces, supermarkets, liquor stores, bowling allies..etc. So why don't we as the Christian church adapt and begin fighting a guerilla war. Quick, agile, nimble, able to move at a moment's notice. One on one, one person, one battle at a time?

Is it me or are we losing the battle because we just have simply set ourselves up for failure by the way we structure ourselves? If this world is not our home, why are we spending so many millions setting up permanent establishments?