Second Coming
The Second Coming (sometimes called the Second Advent or the Parousia) is a Christian and Islamic belief regarding the future (or past) return of Jesus Christ after his ascension to heaven about two thousand years ago. The idea is based on messianic prophecies and is part of most Christian eschatologies.
Millerism
Miller believed that the cleansing of the sanctuary represented the Earth's destruction by fire at Christ's Second Coming. Using the year-day method of prophetic interpretation, Miller became convinced that the 2,300-day period started in 457 BC with the decree to rebuild Jerusalem by Artaxerxes I of Persia. Simple calculation then indicated that this period would end about 1843. In September 1822, Miller formally stated his conclusions in a twenty-point document, including article 15, "I believe that the second coming of Jesus Christ is near, even at the door, even within twenty-one years,—on or before 1843." This document remained private for many years.