“For those who sleep, sleep at night, and those who get drunk, are drunk at night. But since we belong to the day, let us be sober, having put on the breastplate of faith and love, and for a helmet the hope of salvation” (1 Thessalonians 5:7-8).
In addition to the metaphors of day and night given to us above, Paul the Apostle was also fond of using military illustrations to effectively communicate with his audience. In this instance, Paul made use of the armor worn by a first-century Roman soldier to illustrate the proper mindset of a God-honoring man or woman. Although Paul referenced similar types of armor in Romans 13:12 and 2 Corinthians 6:7, the New Testament book of Ephesians offers the greatest amount of detail regarding this concept…
“Put on the whole armor of God, that you may be able to stand against the wiles of the devil… Therefore take up the whole armor of God, that you may be able to withstand in the evil day, and having done all, to stand.
Stand therefore, having girded your waist with truth, having put on the breastplate of righteousness, and having shod your feet with the preparation of the gospel of peace; above all, taking the shield of faith with which you will be able to quench all the fiery darts of the wicked one. And take the helmet of salvation, and the sword of the Spirit, which is the word of God” (Ephesians 6:11, 13-17).
While the attributes of these pieces of spiritual armor differed slightly in each of these letters, their function remained largely unchanged. For instance, a military breastplate protected a soldier’s heart, lungs, and other vital organs much like a bullet-resistant vest serves to protect a law-enforcement officer today. In a similar manner, the qualities of faithfulness, love, and righteousness offer protection from an enemy attack, just as a breastplate protects a soldier. The unrighteous lack this “breastplate” which inevitably leads to spiritual (and perhaps even physical) harm.
A helmet represents another familiar piece of equipment. In work, athletics, or warfare, a helmet serves to protect one’s ability to think, function, and process information. Since a Christian possesses the mind of Christ (1 Corinthians 2:16), the “helmet of salvation” offers protection against the things that might harm us in those areas.
As one commentary summarizes, “The helmet and breastplate defend the two vital parts, the head and the heart respectively. ‘With head and heart right, the whole man is right’.” (1)
(1) Jamieson, Robert, D.D.; Fausset, A. R.; Brown, David. “Commentary on 1 Thessalonians 5:8”. “Commentary Critical and Explanatory on the Whole Bible”. https://www.studylight.org/commentaries/jfb/1-thessalonians-5.html#8