In the book of Zechariah chapter 14 verse 12 there is a vivid and graphic description of what the last day of this earth age will be like, the last 3D day on planet earth.
Using the description in Zechariah, for many years people have tried to teach and proclaim that this description is a description of a Nuclear bomb going off in Jerusalem for it's destruction, but that teaching is not correct at all, it is simply a look at what our flesh bodies will be going through at the last minute of this earth age.
As soon as this description is finished, then we all will be in our new Spiritual bodies from that moment on throughout the 1000 year reign of Y'shua Messiah called the MILLINNIUM period which starts right after this description ends.
At the ending of verse 12, Y'shua Messiah will return at that moment to set up his Kingdom.
The people on this planet that are not Christians and believe not in Y'shua Messiah that he is the savior and son of the true Living God Most High, will also have their Spiritual body as well as believers have, but the non believers will still possess their same soul/Spirit they had as fleshly 3D humans, and they still have the ability to lose their spiritual lives and to follow Lucifer/Satan if they choose to do that.
These people in Spiritual bodies will still be MORTALS, and that means they can still lose their Souls to death if they decide to not accept Y'shua Messiah as their savior during the Millennium period of time.
Those that are already believers before the transformation takes place are "NOT MORTALS" but are already living the 1st Resurrection which makes them "ETERNAL" beings that will live forever, but the non believers still can choose to die if they so desire not to follow the King of Kings to eternity.
The 1000 years will be a period of teaching by Gods Elect to the people of the Earth in order to give them a fair chance to follow Y'shua Messiah into eternity if that is what they choose to do.
GOD MOST HIGH is perfectly fair to all, so that all can make an educated decision at what they wish to do with their souls/Spirit before the Great White Throne Judgment at the end of the 1000 years of time.
Here is the description of the last minute of this earth age.
Zec 14:12 And this shall be the plague wherewith the LORD will smite all the people that have fought against Jerusalem; Their flesh shall consume away while they stand upon their feet, and their eyes shall consume away in their holes, and their tongue shall consume away in their mouth.