EPHESIANS 6:17 NIV 17 Take the helmet of salvation and the sword of the Spirit, which is the word of God.
The sword, or weapon, of the spirit is speaking the Word of God. Left sitting in a book on your shelf, it does you no good.
A weapon must be used against an adversary to be of any benefit. Our adversary is the devil and a weapon he uses is doubt. We must speak God’s Word to actively resist doubt, so it won’t defeat us.
JAMES 1:22 NIV 22 Do not merely listen to the word, and so deceive yourselves. Do what it says.
We need to personalize the Bible, and act on it. The first, and main, way to accomplish this is to speak in agreement with what the Bible says.
For a short basic confession to get you started, look at http://www.believers.org/helps/basiccon.htm