In Isaiah 54:17 the Holy Spirit says, “No weapon that is formed against thee shall prosper; and every tongue that shall rise against you in judgment you shall condemn. This is the heritage of the servants of the Lord, and their righteousness is of me, saith the Lord.”
It’s clear in this verse why no weapon that forms against us will prosper. It’s because of the righteousness of the Lord! Christ's righteousness has been imputed unto us by grace through faith. The Holy Spirit calls this our heritage. Praise God! Truly, whom the Son sets free, is free indeed! The enemy cannot condemn you if you are established in Christ’s righteousness.