When Joshua the High Priest stands before God in filthy clothes, we learn that on our own we stand condemned before God. But the good news is that Jesus has taken our filthy garments on himself and paid for our sin on the cross, and he gives us robes of perfect righteousness. And not only do we stand clothed before God when we put our faith in Christ, but we live in those clothes, as we stand called to point to Christ as testaments to his great grace in our lives.
The strength we need for the Christian life is provided by God himself. Each child of God can lean into the arms of the Father, confident that he who started a good work in us will bring it to completion.
Those who are in Christ are no longer doomed to a life of unrighteousness and condemnation. Rather, in Christ we can live a new life, walking according to the Spirit.