The Millennial Kingdom

In this episode Dr. Betters answers the question, "Howard asks, I was reading about the millennial kingdom in Revelations and a question came to mind. When Christ physically returns to earth and set’s up the millennia kingdom, nonbelievers will be cast into the lake of fire along with Satan. He will rule for a thousand years. At the end of the thousand years, He will release Satan ‘for a short period’ and Satan will create havoc again and Jesus will cast Satan and his followers back into the lake of fire forever. My understanding is that those who follow Satan are human. Now under the belief of ‘once saved, always save’ that implies that children will be born. Is that correct? Have I gone astray in my thinking? What do you think?"