God's Word is a powerful weapon. They have to go because God's Word brings the angels on the scene. God's Word says that He will send out His Word and it would not return void unto Him, but it would accomplish what He sent it out to do. When you speak His Word, you become the voice of God. You are doing the same thing that the prophets of old did. You are speaking what God is speaking. You are taking the Logos, the written word, and making it to become Rhema, the spoken, living word.