Christian eschatology, a major branch of study within Christian theology, deals with the doctrine of the "last things", especially the Second Coming of Christ, or Parousia. Eschatology – the word derives from two Greek roots meaning "last" (ἔσχατος) and "study" (-λογία) – involves the study of "end things", whether of the end of an individual life, of the end of the age, of the end of the world, or of the nature of the Kingdom of God. Broadly speaking, Christian eschatology focuses on the ultimate destiny of individual souls and of the entire created order, based primarily upon biblical texts within the Old and New Testaments.
Christian eschatology looks to study and discuss matters such as death and the afterlife, Heaven and Hell, the Second Coming of Jesus, the resurrection of the dead, the rapture, the tribulation, millennialism, the end of the world, the Last Judgment, and the New Heaven and New Earth in the world to come.
Eschatological passages appear in many places in the Bible, in both the Old and New Testaments. Many extra-biblical examples of eschatological prophecies also exist, as well as extra-biblical ecclesiastical traditions relating to the subject.
Eschatology within early Christianity originated with the public life and preaching of Jesus. Jesus Himself referred to His Second Coming numerous times in the gospels: just a few examples are Matthew 24:27; Matthew 24:37–39; Matthew 26:64; Mark 14:62. Christian eschatology is an ancient branch of study in Christian theology, informed by Biblical texts such as the Olivet discourse (recorded in Matthew 24, Mark 13, and Luke 21), The Sheep and the Goats, and other discourses of end times by Jesus, with the doctrine of the Second Coming discussed by Paul the Apostle in his epistles, both the authentic and the disputed ones. Other eschatological doctrines can be found in the Epistle of James, the First Epistle of Peter, the First Epistle of John.