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 . . .
-- Ephesians 6:13-17
We are commanded to obey, but as we do so, we are commanded here and there to do so after having "Put on Christ" or having "put on the new self." We best be wearing gospel armor when going about God's business.
Notice there are no pieces of effort in the armor of Ephesians 6:13-17. The belt is the truth. What protects our vitals? Righteousness, but not that of ourselves; that is not impenetrable. But Christ's is. Our shoes are the gospel. (They make missionaries' feet beautiful.) When the evil one throws his darts, do we block them with the shield of our law-keeping? No, with the shield of faith. Salvation is, in this metaphor, literally on our minds. We wield not the word of ourselves, but the word of God.
This is armor given, not earned.
Put on Christ (Gal. 3:27). Don't put on the Law. You can try, but even if you were to cover every square inch of yourself with law-keeping, that armor'd be paper thin.