Why is there a population explosion during the Millennium?
During the thousand-year Kingdom Age, flesh-and-blood people enter and continue having children for a thousand years. Because death, sickness, and disease are virtually absent, and conditions resemble Eden, births greatly outnumber deaths throughout that period, producing a tremendous population explosion.
Les explains that those who enter the Kingdom Age as believers become the flesh-and-blood people of that age and will have children for the thousand years. Since there is no death to speak of, no sickness, and no disease, the conditions are much like the Garden of Eden, so the thousand years produce a tremendous population explosion. He notes that the believers are safe for eternity, but their children are still born with Adamic natures. Yet because Satan is locked up and not on the scene to test those natures, there is no real rebellion and no sin; the Adamic nature remains inoperative. Les also calls the Millennium a glorious utopia and a dispensational period, contrasting it with life after Adam and Eve left the Garden, when work, weeds, thistles, sickness, disease, war, famine, and the curse entered.