Do you notice something I drew to your attention in an earlier post - the “although” and the “yet” of Christian experience? This is so true to normal Christian experience. “Although” bad things are happening to the outward man, “yet” very good things are being done to the inward man. On the one hand there is decay, perishing, running down – all negative things; on the other, there is renewal, restoration, regeneration, a kind of rebirth – all positive things.
“Therefore we do not lose heart.” There is no cause why we should lose heart, given that the end of it all is infinitely better than our best times here. The outward man is perishing, but the inward man is being renewed on a daily basis. What we leave behind when we die – our bodies - will return to the dust from which they came, and will rest in their graves until the resurrection. What we take with us into eternity is itself eternal. And one day these will be reunited and made fit to dwell in “the new heaven and the new earth.” To be made fit for this new environment, we have to leave one part behind in order for it to be rejoined later to the other part. We will be changed and fitted for the new dwelling on the new earth.