17 And take the helmet of salvation, and the sword of the Spirit, which is the word of God;
Verse 17 is a mandate to put on other pieces of armor.
17 And take [accept]
The word “take” is imperative, showing that the spiritual warrior is to urgently take up the helmet of salvation and the sword of the Spirit when facing spiritual danger. This is a different word than 6:13, 16. The idea here is welcome. The idea is that we embrace this armor positively.
the helmet of salvation,
The legionnaire Roman soldier’s helmet was made of bronze. Generally, the helmet was not worn on marches, but he put it on during battle. Roman soldiers put on the helmet when facing immediate danger. Otherwise, the helmet was unwieldy and hot. It was made of leather covered with metal plates.
The helmet of salvation protects the mind to think straight biblically. It gives us perspective such as hope (1 Th 5:8). The future is not dire for the Christian; there is a blessed future for him. There is assurance of salvation when we claim the promises of God daily. This is no panacea except for truth derived from the Word of God. Jesus is coming again.
The salvation here is not from the penalty of sin but from the power of sin in the daily struggle with sin.
Assurance of salvation protects the believer from heresy.
The believer’s helmet is his assurance of his personal salvation (2 Ti 1:12; 1 Jn 5:11-13). Salvation is both something future and something present. Here it is something present.
Assurance of salvation protects us against false doctrine. It provides confidence and boldness in the Christian life.