and take the helmet of salvation, and the sword of the Spirit, which is the word of God, (ESV)
As we consider all of the spiritual armor that is needed to protect ourselves from the enemy of our souls, we may very well wonder what we are supposed to use to attack. All of the things we have looked at so far are defensive in nature, and designed to protect us. We now come to our only weapon, the sword of the Spirit, which is the Word of God.
Friends, the Word of God is your only weapon. It is the only one you will ever need. It will never become dull, although your understanding might grow dull. Many people make the foolish mistake of trying to rely on their own abilities to defeat the enemy. As a result, there are wounded Christians, who should have used the Word of God as their weapon. The writer of Hebrews gives a vivid description of just how effective this weapon is:
 For the word of God is living and active, sharper than any two-edged sword, piercing to the division of soul and of spirit, of joints and of marrow, and discerning the thoughts and intentions of the heart. (ESV)
There are two ways in which we must use this weapon. We must first allow it to pierce our own thoughts and intentions. Allow it to show us our sins and failures. Confess them to the Savior, so tha when we do wield this sword against the enemy we do so from a place of purity, not acting in our own strength or self-righteousness.
Are you ready to use the sword? Not so fast. You must know your weapon, so that you will know when and how to use it. I encourage you to "hide God's Word in your heart," as the Psalmist admonishes (Psalm 119). Know the Word and you will be ready to fend off the enemy.