Nobody can stop a tornado. But nobody is strong enough, all by themselves, to handle all of the thoughts, all of the feelings, or all of the forces of evil that are around us and inside of us. We need to have help, and we need to have protection. We need to have invisible armor. The examples that Paul gives are pretty simple.
Truth is like armor.
Truth can overcome evil. Truth is stronger than any outward form of power. If you tell the truth, you never need to be afraid of anything else you've done or said. Truth destroys evil. Another kind of armor, is justice .