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.
Messiah
It is believed that Isa will return to Earth to defeat the Masih ad-Dajjal (false Messiah), a figure similar to the Antichrist in Christianity, who will emerge shortly before "Yawm al-Qiyāmah" ("the Day of Resurrection"). The "Mahdi" will come shortly before the second coming of Jesus. After he has destroyed ad-Dajjal, his final task will be to become leader of the Muslims. Isa will unify the Muslim "Ummah" (the followers of Islam) under the common purpose of worshipping Allah alone in pure Islam, thereby ending divisions and deviations by adherents. Mainstream Muslims believe that at that time Isa will dispel Christian and Jewish claims about him.