The Real "Left Behind" are NOT those who are Left Behind on earth after a supposed Rapture to kick off 7 years before the return of Christ so as to get a "2nd chance".
Rather, the "Left Behind" are those who are "Left Behind" in the dust after His 2nd Advent, resting in death until the end of the millennium.
But the rest of the dead lived not again
until the thousand years were finished.
Revelation 20:5