What is the full armor of God?

from the old testament

• The armor of God is not mentioned in the Old Testament.

from the new testament

• The apostle Paul issued this wisdom to believers in Ephesus: “Finally, be strong in the Lord and in the strength of his might. Put on the whole armor of God, that you may be able to stand against the schemes of the devil. For we do not wrestle against flesh and blood, but against the rulers, against the authorities, against the cosmic powers over this present darkness, against the spiritual forces of evil in the heavenly places. 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 firm. Stand therefore, having fastened on the belt of truth, and having put on the breastplate of righteousness, and, as shoes for your feet, having put on the readiness given by the gospel of peace. In all circumstances take up the shield of faith, with which you can extinguish all the flaming darts of the evil one; and take the helmet of salvation, and the sword of the Spirit, which is the word of God, praying at all times in the Spirit, with all prayer and supplication. To that end, keep alert with all perseverance, making supplication for all the saints” (Ephesians 6:10–18).
• Each piece of the armor of God represents a valuable part of a Christian's arsenal:
• Belt of truth: The belt of truth secures and frees us (John 8:32) from Satan's deceptions (John 8:44). Also, living with honesty and integrity strengthens our spirituality.
• Breastplate of righteousness: The breastplate of righteousness covers the areas that are most vulnerable to attack, such as the heart. Christ’s righteousness guards believers’ hearts (2 Corinthians 5:21).
• Footwear of the readiness of the gospel: We experience peace because we know the good news of Christ (John 14:27) and take steps to serve Him.
• Shield of faith: We can withstand Satan’s attacks because of our faith in Christ (2 Timothy 1:12).
• Helmet of salvation: A helmet protects the brain—basically, the mind. Salvation reassures us of eternity and provides us with inner peace. We have been given the mind of Christ (1 Corinthians 2:12–16). A helmet can also serve as a signifier. When the enemy looks at us, he sees that we belong to Christ. We carry with us the seal of the Holy Spirit (Ephesians 1:13–14).
• Sword of the Spirit: The sword of the Spirit is the Word, which includes God's written Word (the Bible), God's incarnate Word (Jesus as Logos), and God's spoken Word (the Holy Spirit within us). The sword is the one offensive weapon in the list. The Word of God has power, so it is our best offense.
• Prayer: Prayer is an oft-forgotten part of the armor of God, but it is the way we draw strength from God and rely on Him. Apart from this, our efforts in spiritual battle are ultimately futile. First Thessalonians 5:17 tells us to "pray without ceasing."

implications for today

Alarm systems for home and car, insurance for health and goods, and even weapons in case of emergency—there’s no doubt that we do what we can to feel safe. But the biggest threat isn’t a thief or a flood or even a health emergency: It’s our spiritual well-being. Believers are warned that Satan “prowls around like a roaring lion, seeking someone to devour” (1 Peter 5:8).

How might he do this? Maybe he whispers in your ear that the Bible is hard to understand, so just give up on reading it and scroll on your phone instead. Or maybe he causes dissension in your church, so much so that you stop going. Or maybe he tempts you with what he knows is your weakness.

We can’t win—if we try in our own strength. But we can’t lose—if we put on the armor God has given us for protection. Christians have all the resources we need to defeat the enemy.