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).

6:18 Praying always. Persevering prayer, not just for personal deliverance, but also in supplication for others, is the invisible, but powerful, weapon that assures that God Himself, with His angels, is also fighting for us.

6:19 mystery. Once again (see also Ephesians 1:9; 3:3-4,9; 5:32), as he closes the epistle, Paul speaks of that past mystery hidden in God since creation, which he now wants boldly to make fully known.