The helmet of salvation (thn perikepalaian tou swthriou). Late word (peri, kepalh, head, around the head), in Polybius, LXX, 1 Thessalonians 5:8 ; Ephesians 6:17 alone in N.T. Which is the word of God (o estin to rhma tou qeou). Explanatory relative (o) referring to the sword (macairan). The sword given by the Spirit to be wielded as offensive weapon (the others defensive) by the Christian is the word of God. See Hebrews 4:12 where the word of God is called "sharper than any two-edged sword."