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.
Jehovah's Witnesses beliefs
Watch Tower Society publications teach that Jesus Christ began to rule in heaven invisibly as king in October 1914. They assert that the Greek word "parousia" (translated in most English Bible translations as "coming" when referring to Christ) is more accurately rendered "presence", perceived only by a composite "sign". As such, the Second Coming is considered an invisible presence, lasting for an extended period of time, and ending with Jesus' "coming" to separate the Sheep and the Goats. They believe that when Jesus became king, Satan was ousted from heaven to the earth, bringing a period of "woe" to mankind.