Many questions come to mind when I consider the heading, “Putting on the Breastplate of Righteousness.” I will set out to examine the two most obvious questions. First, for the simple observation of the question; “What is the function and purpose of a breastplate of armour”? Its function is to protect the torso, in the purpose of protecting the heart, for the heart is man’s life in and of the body. But in this passage, the apostle is speaking not in the corneal sense, but in a spiritual sense. Which leads me to my second question. What is righteousness? Scripture tells us, “there is no one righteous, not even one,” Romans 3:10, but only God. Righteousness is perfect love through faith, this is why Jesus said, “If you love God with all you heart, mind, soul and strength, and your neighbor as yourself you have fulfilled the entire law.
But how do we accomplish this seemingly impossible command? Does anyone love anything perfectly? Galatians 5:17 says “the desires of the flesh are against the spirit, and the desires of the spirit are against the flesh;” to prevent you from doing what you would. But if you are led by the spirit you are not under the law. The fruit of the spirit are these, love, joy, peace, patience, kindness, goodness, faithfulness, self-control, against such there is no law. Those who belong to Jesus Christ have crucified the flesh with its passions and desires. Let us live and walk by the Spirit in faith and not by sight. Thanks be to God, he has made a way to perfection, faith in God, through our Lord Jesus Christ, and the love poured into our hearts by the Holy Ghost is the way.
In the Old Testament God wrote his laws on stone tablets to bring to mind the awareness of our evil works, but in the New Covenant He wrote His laws on our hearts and minds, and for those who believe have put on the law of righteousness, and now have the law of faith and the spirit given to them is life to those who love. Hebrews 8:10-11; therefore no one can say ,”I didn't know right from wrong.” By putting on the breastplate of righteousness, which is Jesus Christ’s righteousness, is affected by grace (a free gift from God) through faith (to believe), day by day (a daily conversion process).
There are several factors that can interfere with the effectiveness of our spiritual breastplate, both venial and mortal sin will block grace. In pushing forward through life in his pursuit of joyfulness, man must continue to fight against the world the flesh and the devil, this life we live is our training course, and for those who sacrifice well in faith, and do good works is proof of their devotion toward God and neighbor. James 2:20,... “faith without works is useless.”
Righteousness can not be attained perfectly in this life absent of our Lord, this is why it is said we walk by faith and not by sight, but in perseverance through our Lord Jesus Christ we hope to see God face to face, and our righteousness will be complete in the sight of His glory. For this perishable must put on the imperishable, and this mortal must put on immortality. 1 Corinthians 15:53-55; But when this perishable will have put on the imperishable, and this mortal will have put on immortality, then will come about the saying that is written, “DEATH IS SWALLOWED UP in victory. “O DEATH, WHERE IS YOUR VICTORY? O DEATH, WHERE IS YOUR STING?” The sting of death is sin, and the power of sin is the law; but thanks be to God, who gives us the victory through our Lord Jesus Christ.
Now we hold firm to working out our salvation with virtue, faith, hope and most of all charity; against charity there is no law. By keeping our bodys in subjection, doing alms, fasting cheerfully, and heartfelt prayer; forgiving those who sinned against us and asking for forgivness of our trespassess, and doing this all on sound doctrine we commit ourselves to the Way the Truth and the Life. This is now our breastplate of righteousness, in which we pass through our course hungering and thirsting after the perfect and full righteousness, in order that we may hereafter be satisfied therewith. Jesus commands do not do in order to be seen by men but in secret unto God who sees in secret. Now in the fasting He indicates the entire subjugation of the body; in the alms, all kindness of will and deed, either by giving or forgiving; and in prayers He implies all the rules of a holy desire, this is living by the spirit. So that, although by the subjugation of the body a check is given to that concupiscence, which ought not only to be bridled but to be put completely out of existence. However in doing our good works (which is alms) for the good of others there may be a hint of unfairness that tarnishes that cheerfulness, but depending on the progress of his generosity, God will give him the reward so long as he is sincere; and yet for this reason we must pray “forgive us our tresspasses as we forgive those who trespass against us. For the way in which we walk, that is, the road by which we reach perfection, is cleansed by clean prayer. That, however, is a clean prayer in which we say in truth, Forgive us, as we ourselves forgive. Matthew 6:12.
1 Peter 5:6-11, Bow down, then, before the strong hand of God; he will raise you up, when his time comes to deliver you. Throw back on him the burden of all your anxiety; he is concerned for you. Be sober, and watch well; the devil, who is your enemy, goes about roaring like a lion, to find his prey, but you, grounded in the faith, must face him boldly; you know well enough that the brotherhood you belong to pays, all the world over, the same tribute of suffering. And God, the giver of all grace, who has called us to enjoy, after a little suffering, his eternal glory in Christ Jesus, will himself give you mastery, and steadiness, and strength. To him be glory and power through endless ages, Amen. ( :source: http://www.newadvent.org/)