And take the helmet of salvation, and the sword of the Spirit, which is the word of God:
The next piece of armor is the helmet (4030 perikephalaia; encirclement of the head, i.e. a helmet:) of salvation (4992 soterion; defender or (by implication) defence:). Our head is not protected by ourselves. Instead, our head is encircled by salvation - which comes from Jesus Christ.
This concept reminds me of the references to Christ as the Head of the church.
"Jesus saith unto them, Did ye never read in the scriptures, The stone which the builders rejected, the same is become the head of the corner: this is the Lord's doing, and it is marvellous in our eyes?" (Matthew 21:42)
"But I would have you know, that the head of every man is Christ; and the head of the woman is the man; and the head of Christ is God." (1 Corinthians 11:3)
"And hath put all things under his feet, and gave him to be the head over all things to the church, Which is his body, the fulness of him that filleth all in all." (Ephesians 1:22-23)
"For the husband is the head of the wife, even as Christ is the head of the church: and he is the saviour of the body." (Ephesians 5:23)
"And he is the head of the body, the church: who is the beginning, the firstborn from the dead; that in all things he might have the preeminence." (Colossians 1:18)
"And ye are complete in him, which is the head of all principality and power:" (Colossians 2:10)
The verse that especially seems to connect this concept is Ephesians 5:23, "For the husband is the head of the wife, even as Christ is the head of the church: and he is the saviour of the body." Christ is the head, the Savior. We are to take the helmet of Salvation.