it is.
the saints come back to rule and reign for 1000 years. the world is a mess and needs order. it will take time. during this time there will be mortal and immortal people. people will be able to accept Christ as savior and lord. nations will bring tributes to Christ who reigns from Jerusalem.
even with all this some will not believe. satan is loosed at the end of this period and is able to deceive the unbelievers at this time to try to overthrow God, and they will fail.
The Nephelim: TRUE STORY of Satan, Fallen Angels, Giants, Aliens
Recall the famous quote by Shakespeare in Hamlet: "There are more things in heaven and earth, Horatio, Than are dreamt of in your philosophy . . . "