Eph. 6.10-18 records Paul’s admonition to deploy weapons, both defensive and offensive, in the struggle against evil. The idea of both types of weapons comes from the list itself where these descriptions denote either offensive or defensive purposes. Also, in 2Cor. 6.7, Paul instructs to use “weapons of righteousness on the right and left.” It doesn’t take much insight to see the typical soldier of that day with a shield in left hand and sword in his right – one offensive and the other protective.
Most English versions, in their formatting, do not include v. 18 in the list of armor. It should be included, however, just as militaries rely on communication in their battles, so Christians can depend on God’s provision in the struggle.
Therefore, Paul’s list divides structurally as two groups of three with Faith as the center. ‘The faith’ is what we preach (Rom. 8.10). Also, without faith it is impossible to please God (Heb. 11.6). Faith is the center since everyone has had intimations from Him: Since what may be known about God is plain to them, because God has made it plain to them (Rom. 1.19 NIV).
Here is my translation of Eph. 6.10-18 which seeks to provide a flow for memorization:
From now on, be empowered by the Lord and His mighty strength. Put on the whole armor of God to be able to stand against the schemes of the devil. For our struggle is not against flesh and blood but against the rulers, against the authorities, against the cosmic powers of this darkness, against the spiritual forces of wickedness in the heavens. Therefore, take up the whole armor of God in order to withstand in the evil day, having done everything to stand. Stand therefore having gird yourselves with truth and having put on the breastplate of righteousness and the feet fitted with the preparation of the gospel of peace. Besides this, take up the shield of faith with which you will be able to quench all the flaming arrows of the evil one. Put on the helmet of salvation along with the sword of the Spirit (which is the word of God). With all prayer and petition, praying all times in the Spirit, with this in mind, watch and persevere in petitioning for all saints.
Paul mentions the panoply (vs.13), which refers to a complete suit of armor designed for battle. Partial armor will leave the wearer exposed in places; therefore, all of the mentioned items are vital. The foes are fallen spiritual entities over the world (cosmos). These dark forces traverse both earth and heaven, temporarily, and seem to be marshalled into various ranks against us. Therefore, Christians need to do everything to stand firm in Christ.
Truth as a belt: The Greek doesn’t mention a belt; instead, “girding truth around the waist.” The sense is a belt without explicitly saying it. The idea is to acquire the truth of scripture in a full and comprehensive way and to stand and defend when asked. There are many false and dumb ideas in society today, and for the Christian, they are to be assured in their mind of the truthfulness of scripture. This weapon seems more defensive in purpose but may also project a quiet confidence which will send a message to the opponents and other observers (see Phil. 1.28).
The breastplate of righteousness refers to love and faith, fastened around one’s neck, with these qualities written on the tablet of the heart (see Prov. 3. 3-4). Also, Paul defines what this breastplate is, in 1 Thess. 5.8: But since we belong to the day, let us be sober, putting on faith and love as a breastplate, and the hope of salvation as a helmet. This item of armor appears defensive in nature as well.
The Boots of preparation is an offensive weapon by which Christians are ready to hold forth the good news of Jesus’ death and resurrection for humanity’s justification. In the Greek, no shoes are mentioned, instead, feet are to be fitted. Some sort of footwear is implied however to aid the feet in the journey, and, of course, to stand. Importantly, it is not just a preprogramed scheme such as the “Roman’s Road” where the lost are guided by only a few simple truths. Instead, the Christian should be prepared to speak in bible concepts at points where the inquirer has questions. Sharing one’s faith with others should not be forced in any way. Instead, it should possess an element of spontaneity and flow naturally. Speaking about God is the most natural thing to do. This is His world, after all. On the other hand, if someone is not receptive, the Christian is not to give what is holy unto dogs, or cast their pearls before pigs.
The shield of faith is primarily defensive and resembles the breastplate which has as one of its elements faith or faithfulness. The difference seems to be that the breastplate is more intimately attached to the vital parts of one’s constitution whereas the “shield of faith” is held more at a distance to stop general types of attacks.
The helmet of salvation refers to the assurance one has as they walk with the Lord. As mentioned in 1 Thess. 5.8, it is “the hope of salvation.” Hope here means something substantive, a confidence that the believer will experience the joy of the Lord after passing this veil of tears. This assurance will need to be constantly bolstered as the Christian does what is right in every circumstance: The effect of righteousness will be peace, and the result of righteousness will be quietness and confidence forever (Is. 32.17 NET). This item, by its nature, protects and is, therefore, generally defensive.
The sword of the Spirit is defined for us in the text and is no mystery what it accomplishes: a thrust of truth. This must be wielded in love, however, since: but, speaking the truth in love, we are to grow up in all aspects to Him who is the Head-Christ (Eph. 4.15).
Prayer in the Spirit is accomplished when Christians, who have the Spirit, are no longer relying on themselves for wisdom. Prov. 3.5 is instructive: Trust in the Lord with all your heart and do not lean on your own understanding. It is a choice for Christians to walk in the Spirit or be led by their old selves. Prayer in the Spirit is more typical after God has crushed all our idols. Those Christians determined to follow God will know how to pray to Him. This prayer is not only self-focused, or humanity-focused, but looks after the needs of other Christians. We need to persevere in prayer for the needs of all Christians.