When Paul the apostle wrote his letter to the church at Ephesus, he was under house arrest chained to a Roman soldier. He wrote about the spiritual war being waged all around us on planet earth. He used the Roman soldier’s armor as an analogy of the spiritual armor of protection to gain victory over our opponent, the fallen angel, Satan. When Paul looked at the Roman soldier’s breastplate, it reminded him of how a Christian needs the breastplate of righteousness to defend the heart and inner organs. Two possibilities could have been in Paul's mind as he wrote.
1) The first is the need for imputed righteousness. What do we mean by imputed? Imputed means credited to our account as when God spoke to Abraham, our father in the faith, and told him that he would be a father to a multitude of people even though he was old and childless.
5He took him outside and said, “Look up at the sky and count the stars—if indeed you can count them.” Then he said to him, “So shall your offspring be.” 6Abram believed the Lord, and he credited it to him as righteousness(Genesis 15:5-6).
Abraham believed God’s word. What was God's response to Abraham's faith? Scripture says that righteousness was credited to his spiritual bank account (Genesis 15:5-6). Imputed righteousness puts us in right standing before God, allowing God to come and live within us by His Spirit. Our right standing with the Lord is not due to our efforts; it is given as a gift when we believe (Romans 4:1-8). God has been so generous and kind toward us in dealing with us in this way. He treats each of us as believers in the same way as He handled Abraham. The Lord imputes the righteousness of Christ to us as a gift when we believe in the substitutionary work of Jesus on the cross, bearing your sins in His body (1 Peter 2:24). When we believe He credits righteousness, i.e., the righteousness of Christ, to our spiritual bank account:
God made him who had no sin to be sin for us, so that in him we might become the righteousness of God (2 Corinthians 5:21).
When the enemy comes to you with accusations of what you have said and done wrong, we can reply that Jesus cried out from the cross, “It is finished” (John 19:30). The Greek word translated “finished” is an accounting term, which means paid in full. He has paid my debt of sin. There is nothing that can be done to add to the righteousness that Christ imparts to us when we place our trust in Christ. It is not ninety-five percent of Jesus' work and five percent of our work. It is all of Jesus! Christ fully paid the debt. The believer who knows what Christ has done for him can laugh at the enemy's vain attempt at saying that the believer is not good enough. Christ is our righteousness.
2) Paul could also be pointing out that the breastplate of righteousness speaks of walking a life of right living before God. If this is the interpretation to which Paul was referring, he may have been concerned that the enemy’s darts could find a lodging place in the heart of a believer if he or she is not living a life of confession and repentance. We are to walk in the light as He is in the light:
7But if we walk in the light, as he is in the light, we have fellowship with one another, and the blood of Jesus, his Son, purifies us from all sin. 8If we claim to be without sin, we deceive ourselves and the truth is not in us. 9If we confess our sins, he is faithful and just and will forgive us our sins and purify us from all unrighteousness (1 John 1:7-9).
Living in God's forgiveness calls for a life of vulnerability before God and others. The enemy's darts of accusation and condemnation cannot lodge in the heart if one is living a life of obedience and right living before God and his or her brothers and sisters in Christ. When we sin, we need to be open and vulnerable to God and agree with Him about it. Ask Him for forgiveness, and if something was done to someone else, to get it right with that person. Sometimes, restitution is needed. If so, don't delay in paying it. Keith Thomas
This meditation is a shortened version of the more in-depth study: The Armor of God.