Before creation, God freely decided to be our God in Christ. No one decided this for him. Deep within his own Triune life He gladly chose to be God for us as one of us. All flowed freely from the fullness of Triune love.
We have turned away rejecting His free decision to be our God. So we have proved ourselves unworthy of His decision for us. Furthermore, in our entire history, we have demonstrated that we are unable to reconcile ourselves to God. We cannot find our own way back to God or provide a saviour from among us. If we are to be saved from ourselves then the Saviour must be from God. No! The Saviour must be God Himself. In free love He must reconcile us to himself. And that is just what He has done in Jesus. He is not a mere agent that God made use of for our salvation. He is God Himself acting among us as one of us to bring us back home.
God also acts in love to bring to completion the reconciliation that He has accomplished in Jesus. The Father, who sent the Son, sends the Spirit of His Son in order to unite us with Jesus, by faith. Now we are in Jesus and Jesus is in us because the Spirit binds us to him in living union. And in that living union we are brought back home to our Father so that we share in the Son’s love relationship with the Father by the Spirit.