"...and the sword of the Spirit, which is the word of God:" (Ephesians 6:17)
The Bible has so many promises one can claim and principles to apply. One of the reasons I like listening to good preaching is that it helps me understand the Bible clearer so that I can take the sword of the Spirit and defend sound doctrine, or attack false doctrine. Jesus gave us His example in fighting and defeating Satan's temptations by using Bible verses (Matt. 4). It is for this reason that Bible study is a serious matter. Whether it is a private and personal study, or even a Sunday School lesson, such an endeavor demands our utmost attention and careful consideration.