There shall be no more thence an infant of days, nor an old man that hath not filled his days: for the child shall die an hundred years old; but the sinner being an hundred years old shall be accursed.
21 And they shall build houses, and inhabit them; and they shall plant vineyards, and eat the fruit of them.
Verse 20 speaks to a change in the length of human life.It will be prolonged so that men will live as long as trees (v. 22) and for the entire 1,000 years of the Millennium if they do not commit a sin having the death penalty, an act which will require them to be executed. Then, if they do not rebel with Satan at the end of the Millennium, if they have accepted Jesus Christ as their Saviour; if they are born again and consecrated to eternal righteousness, they will continue to live eternally in the new earth (Matt. 25:46; I Cor. 15:24-28). A man in the 1,000-year reign of Christ will be considered an infant of years instead of an infant of day and no one will die unless he is executed for crime; nobody will fail to fill out his days of maturity and long life. Even sinners will live through the entire period if they will obey the civil laws and refrain from sins that carry the death penalty. A man will be considered a mere child at the age of 100.
Verse 21 describes that normal day to day life will continue; people will marry, have children, build houses, work in their vineyards and fields, and enjoy the fruit of their labors. All will be prosperous, building and living in their own homes; the days of mortgages, credits, debts, and other bondages of the present economy will be a thing of the past (Mic. 4:4; Zech. 3:10)