God doesn't "own" us, and nor do we have our bodies "on loan" (as someone else had suggested - to whom I replied). There is nothing in the Catholic faith which supports what he and you seem to think about the alleged 'loaning'  or 'ownership' of the body.
We have everything from God. Life (including our bodies) is a gift from God. If we live as God wants us to, with the Spirit within us, we may be said to belong to Him (and to be with Him) still. But this is nothing so crude as any talk about 'ownership' or 'lending' of bodies.
God is 'fit to judge' (as you put it) because He is God.