The Second Coming (Parousia in the Greek meaning "arrival") is a term in Christian Eschatology to describe the return of Jesus to earth that will occur in the future.
The Second Coming was prophesied by Christ himself and by St. Paul. No one will know the date, but it will come "like a thief in the night" (II Peter 3:10)
See also Great Apostasy.
The New American Desk Encyclopedia, Penguin Group, 1989