6:16 shield of faith. The Roman shield was metallic and thus invulnerable to the ignited missiles often fired by opponents, especially when the entire phalanx mounted shield adjacent to shield, giving a solid wall of advancing metal. The shield is faith, and faith in God’s promises is “the victory that overcometh the world,” especially that promise that the Creator, the Son of God, has also become, in Jesus Christ, our eternal Savior and Lord (I John 5:4-5).

6:17 helmet of salvation. This helmet is called “the hope of salvation” in I Thessalonians 5:8, and such a hope is, indeed, a hope involving “full assurance…unto the end” (Hebrews 6:11). Salvation involves an eternal future salvation as well as a past acceptance and present assurance thereof. It is that certain hope that protects the believer’s mind as he would, in this spiritual warfare, seek continually to be “casting down imaginations, and every high thing that exalteth itself against the knowledge of God, and bringing into captivity every thought to the obedience of Christ” (II Corinthians 10:5).

6:17 word of God. The “sword of the Spirit” (note Hebrews 4:12) is not the logos (that is, the Word as a whole) but the rhema (that is, the individual text, or “saying,” of the Word) that is applicable in each particular situation and Satanic attack. Thus Jesus defeated Satan at each temptation merely by citing the appropriate Scripture (Matthew 4:4,7,10).