The sword of the Spirit, which is the Word of God. Ephesians 6:17
Eternal life is in God’s Word
For dead and dying men;
By it alone we know the Lord,
Unseen by mortal ken.
O blessèd Word, O gracious Word,
We’ll love thee more and more;
Be thou our life, our strength, our sword,
’Till earthly strife is o’er.
God’s strength is in His holy Word;
We need it every day;
In all our conflicts this the sword
Our spirit foes to slay.
By this same Word we know our task,
And how it should be done;
How now to live, and how at last
Our crown is to be won.