What is the purpose of Satan's return at the end of the tribulation?
Satan is released to test the new generations born during the thousand-year reign who had never made a personal choice, thereby proving the innate rebelliousness of the Adamic nature. His return serves that specific purpose, and those tested will again follow Satan.
Les explains that after the thousand-year perfect rule, children are born to believers who came in at the front end and have never had to make a choice. Therefore Satan must be released so their choice can be tested. He comes back at the end of the tribulation for that specific purpose, to try and test these new generations who have before never made a choice. And again they are going to follow Satan.