Isa 54:17 NKJV “No weapon formed against you shall prosper, And every tongue which rises against you in judgment You shall condemn. This is the heritage of the servants of the LORD, And their righteousness is from Me," Says the LORD.”
The only way that this promise is to you and for you is if you are resting in *the righteousness of God* provided as a free gift for trusting in Jesus. The reason is that the righteousness of God is the defense against the weapons of the enemy. Who is the enemy? In Revelation chapter 12 he is called the accuser of the brethren. In fact, he accuses them day and night before the Lord. What are the accusations used? They are always a form of the statement “you can’t be righteous because.” The accuser of the brethren and sisters too… brethren was meant to be all believers… accuses us by suggesting that we are not really righteous. He assaults the idea that we have been declared righteous by God and therefore are the very righteousness of God. Look at the verse in the amplified Bible: (Isa 54:17 Amp) “But no weapon that is formed against you shall prosper, and every tongue that shall rise against you in judgment you shall show to be in the wrong. This [peace, righteousness, security, triumph over opposition] is the heritage of the servants of the Lord [those in whom the ideal Servant of the Lord is reproduced]; this is the righteousness or the vindication which they obtain from Me [this is that which I impart to them as their justification], says the Lord.” The righteousness of God is your heritage. It is your inheritance.
So then, the very foundation for your righteousness before God is based upon the free gift given by grace and grace alone. If, you are not 100% sold out to belief in your righteousness because God has declared it, the weapons will come, and come, and come and they will prosper. The reason for defeat in so many saints’ lives is this cause. They are not really, truly resting in the righteousness of God. The Sabbath Rest, Hebrews 4:10, is important in not allowing weapons, formed by the enemy to prosper. Our justification and our peace with God (Romans 5:1) is the source of our warfare.
When we believe that our righteousness is from our good works, that we are acceptable to God by our works, we always open the door for accusation. Accusation is Satan’s weapon of choice. Since we know that we do not stack up favorably before a Holy God with our righteous acts we always feel condemnation and failure. This is the place where the enemy of our souls finds the most effective weapons to use against us. However, when we truly rest in the righteousness of God provided for us as a free and unmerited gift, we can put to flight the enemies accusations. We merely need to declare what God has already decreed about us and Satan must flee. His weapons lose their power.