The last piece of the Armor of God is the sword of the Spirit “which is the Word of God.” The history of mankind is usually punctuated entirely by war. Life proceeds until war consumes. A new life proceeds until another war 
consumes. Someone said that the history of mankind has less than 300 years in which peace was the norm. War is the norm for us! We live by the sword. Jesus once said that “if you live by the sword you will die by the sword” (Matthew 26:52). In that context, Jesus was responding to Peter’s attack on Malthus in which he cut off his ear. One who lives a violent life, will die a violent death. Taking up the “sword of the spirit” is not taking up a literal sword. It’s the word of God.
MacArthur observes, “Now when we think of a sword, we usually think of a long thing that someone flails around. The Greek word for that type of sword is rhomphaia. But the Greek word used here is machaira, which refers to a short, small dagger. The sword of the Spirit, therefore, is not a huge sword that you just flail around, hoping that you’ll whack off the head of a demon sooner or later. It is not something you use indiscriminately or wildly. But the sword of the Spirit is a machaira; it is a dagger, it is incisive, it must hit a vulnerable spot or it doesn’t do any damage. The sword of the Spirit is not something general, but specific.”
When we see the phrase “Word of God” we are often looking at the English translation for the Greek word “Logos” for word. But this is not the case in this phrase. The word here is “Rhema.” I’m certain I can’t say it as well as MacArthur does, so let me quote him again. “When the Bible wants to speak of a specific, it uses the word rhema. Now it means ‘a specific statement.’ So the sword of the Spirit is the specific statement of the Word of God that meets the specific point of temptation.” I’ll add to MacArthur’s comment by reminding you that this is exactly how Jesus used God’s Word as he refuted Satan’s temptations while he fasted in the desert. MacArthur continues, “Now some people may say, ‘Well, I have the sword of the Spirit—I own a Bible.’ Listen, you could own a Bible warehouse, and you wouldn’t have the sword of the Spirit. Having the sword of the Spirit is not owning a Bible, but knowing the specific principle in the Bible that applies to the specific point of temptation.” Let me then, remind us all of the importance of studying God’s Word (logos), the bible. From it comes God’s word (rhema). It’s the comprehension and application of the truth of the principles of scripture that is the source of victory.