Ephesians 6:17 “Also, take "the helmet of salvation," and the sword of the Spirit which is the Word of God;”
The helmet protected the head. One blow to the head could end up being fatal.
The helmet was made of leather or brass. It was usually crowned with a plume or a crest. On that crest and on other parts of the helmet were emblems.
The Christian helmet is our hope in salvation. As the helmet protected the soldier from the blows of the enemy, our hope in salvation protects us from the blows of the devil. It's that hope that gives us the courage to face the battles in our life. We know we're going to win this war. Christ already took our fatal blows and died for us. Because of Him, and only because if Him, we are winners. When the devil tries to strike us down with blows, hold up the shield of faith and keep your head up. You have hope. You have the helmet of salvation!
The sword was an essential part of the armor for the soldier. No soldier would have gone into battle without his sword. The Christian sword is of the Spirit which is the word of God. It is the Spirit which inspired the people who wrote the Bible and it is the Spirit who brings texts to a person's mind just when they need it. When the devil comes at a Christian with temptations or trials, the Christian can fight back with the Bible. Jesus met the devil with texts from the Bible and messed up the devil's plans. We can do the same when temptations come our way. Respond to those temptations with scripture. This is why it is so important to read the Bible and learn what is written in there. When the time comes that we are facing temptation or going through some kind of trial the Spirit will bring to the mind the texts that are needed to fight those difficulties. The person who tries to go through life without the Bible as his guide or sword is a person who will fail miserably.
Knowing what is in the Bible is essential to every Christian. In order to gird oneself with truth, the Bible is needed to know what is truth. To be able to have a breastplate of righteousness, one has to read the Bible to know about Jesus and then understand the need to accept Him and His gift of righteousness. A person cannot spread the gospel of peace if they haven't read the Bible to know about it. Without the Bible there would be nothing to have faith in, so there would be no shield of faith. There would be no helmet of salvation if one didn't read the Bible and know about Jesus and the salvation we have because of Him.
We cannot know of the armor of God, or even put it on, if we didn't first get the sword (the Bible), examine it, and learn from it. The person without the Bible is an unarmed soldier.