"Gird up your loins with truth"
What does this mean? Well you have to look at the historical perspective and the cultural perspective when studying this phrase. It has to do with what people wore in that time period, and specifically what the Roman Soldiers wore when they dressed for battle.
Truth matters. How much does it matter? It affects your entire preparation for spiritual warfare and determines your success rate when it comes to winning battles and achieving the goals you have as a soldier in the Christian army.