A human person requires a cosmos to sustain it: of anyone it is literally true that the whole world is her body, since the light of the sun, and the respiration of algae, are essential to her bodily survival.
If there is a human person who is God, then the whole world, centered on that person, is God’s body.
As further elements of that one body become obedient to God, the world is healed: we may, bizarrely, speak as if God’s body is at present maimed by human or demonic rebellion. On this account, perhaps, God renews His involvement with the world of finite things by making them His body (as once, before His limbs rebelled, it was). Only because He is more than the cosmos can He heal the cosmos.
Incarnation gives us all that honest pantheists can really want: at present we are not God, but hope to join Him.
Stephen R. L. Clark in God, Religion and Reality.