Spurgeon writes -

Paul does not paint the future with rose-colour: he is no smooth-tongued prophet of a golden age, into which this dull earth may be imagined to be glowing. There are sanguine brethren who are looking forward to everything growing better and better and better, until, at the last this present age ripens into a millennium. They will not be able to sustain their hopes, for Scripture give them no solid basis to rest upon. We who believe that there will be no millennial reign without the King, and who expect no rule of righteousness except from the appearing of the righteous Lord, are nearer the mark. Apart from the second Advent of our Lord, the world is more likely to sink into pandemonium than to rise into a millennium. A divine interposition seems to me the hope set before us in Scripture, and, indeed, to be the only hope adequate to the situation. We look to the darkening down of things; the state of mankind, however improved politically, may yet grow worse and worse spiritually.