In the hymn, "A Mighty Fortress Is Our God," verse 3, what is that "one little word"?
Answer: The "little word" of vs. 3 is "That Word above all earthly powers" in vs. 4 - the living Word of God incarnate, Jesus Christ (John 1:1-3,14ff, "the right man on our side, the man of God's own choosing") and (inseparably linked to Him) the Word of God written (the Bible) which comes from Christ by the Holy Spirit and reveals Him to us, which the Holy Spirit uses to work victorious faith within us, His truth that abideth still.
The "little word" looked like a weak nothing hanging on the cross while the prince of darkness raged against Him; now He reigns in triumph, having felled the prince of darkness (John 12:31, 16:11, Col.2:15, Matt.12:28, 29, Rev.12:1-12), and His kingdom is forever. Now when the devil or his demons come threatening, though we have no strength of our own in which to confide, that "little word" is all we need to stand against the devil and his demons; that "little word" still fells them.
I like this explaination!!!