I. It is promised that their houses shall be rebuilt (v. 4), that their cities shall be raised out of the ruins in which they had long lain, and be fitted up for their use again: They shall build the old wastes; the old wastes shall be built, the waste cities shall be repaired, the former desolations, even the desolations of many generations, which it was feared would never be repaired, shall be raised up. The setting up of Christianity in the world repaired the decays of natural religion and raised up those desolations both of piety and honesty which had been for many generations the reproach of mankind. An unsanctified soul is like a city that is broken down and has no walls, like a house in ruins; but by the power of Christ's gospel and grace it is repaired, it is put in order again, and fitted to be a habitation of God through the Spirit. And they shall do this, those that are released out of captivity; for we are brought out of the house of bondage that we may serve God, both in building up ourselves to his glory and in helping to build up his church on earth.