Jesus acts in our place and in our cause as only he can. He alone “gave himself for our sins to set us free from the present evil age, according to the will of our God and Father”(Gal. 1:4). We did not play any part in this saving action. How could we? We were under the power of the present evil age unable to do anything for ourselves and so unable to add to what Jesus did for us. He was also made a curse for us to free us from the curse (Gal. 3:13). Again, he did so, without us. The whole of God’s saving action has happened fully in Jesus needing no completion by us.
But is there no way at all that God’s saving action is completed by us? What about the decisive demand of faith? Faith is vital, but it does not add to what Jesus has done for us. In faith we gratefully respond to all Jesus has done for us by trusting in Jesus plus nothing. We fully trust in him alone and not at all in ourselves. And we give thanks to God for his indescribable gift.
This faith comes as Jesus encounters us personally by his Spirit. And in this encounter we know that faith is the gift of God. Furthermore in this response of faith we are united to Jesus by his Spirit. And in this union we now share personally in Jesus response of faith in our place and on our behalf. In that way, our imperfect response of faith shares in the perfect faith of Jesus on our behalf. It is all Jesus plus nothing.