Redeemed humanity is young

So has the world been gradually going to hell for 2000 years until Jesus comes back to fix everything (as the pre-mil dispensationalists claim), or is it gradually (sloooooooowwwly and sometimes invisibly) being redeemed and everything bought under the lordship of Christ, as the post-mil and some a-mil folks say? What did Lewis say?

It is like when you throw a stone into a pool, and the concentric waves spread out further and further. Who knows where it will end? Redeemed humanity is still young, it has hardly come to its full strength. But already there is joy enough in the little finger of a great saint to waken all the dead things of the universe into life.

-C.S. Lewis, The Great Divorce, p.106