Eschatology is the term used to describe what the Bible teaches about how the present order and age will end. The present age began with creation (Gen 1:1) and continues under God's grace (Neh 9:6) and will conclude with the ultimate reign of God over all things (1 Cor 15:24, 28).

Definitions
The word eschatology does not appear in the Bible but the idea is found throughout. It is made up of two Greek words: εσχατος which means last/end and word or teaching. So eschatology refers to Biblical teachings about the last days or end times.

Later or latter
Later refers to some events in the end days (1 Tim 4:1;  James 5:7;  2 Peter 2:20).

Last
The adjective last appears continuously in relation to events and circumstances during the end times (2 Tim 3:1;  2 Peter 3:3;  1 John 2:18).

End
End also refers to eschatological events (Mt 24:3,6, 13f, 39f).

Age (or world)
Age occurs in many passage discussing the end times (Mt 12:32;  Mk 10:30; Jn 6:51;  2 Cor 11:31;  Eph 3:21;  Rev 1:6).

The only source of information about the future is the Bible (2 Pet 1:20). The whole Bible is prophecy (Inspired directly by God). Two types of prophecy can be found in the Bible: historical which speaks of things that have already happened, and predictive which speaks of things which are still to occur.

Two kinds of eschatology

Eschatology mostly deals with predictive prophecy. God alone knows the future (Isa 46:9-10). About a third of the Bible contains predictive prophecy. There are many prophecies concerning the coming of Christ two thousand years ago but there are many more concerning his return at the end times.
We are also given information about the future in historical prophecy. The end times will develop out of historical events.

The parousia (coming or arrival) of Christ
The essence of eschatology is the parousia of Christ. The Old Testament does not distinguish between the coming of Christ and his return a second time at the end times. This becomes clear in the New Testament.
The end times began when Jesus arrived two thousand years ago (Heb 1:2;  9:26;  Acts 2:17;  1 Cor 10:11;  1 Jn 2:18;  1 Cor 15:23;  Rev 1:3)
The return of Christ will conclude the present age with a transition into the new age.

God has a plan for history and a future program for bringing it to fulfilment. It must come to pass (Rev 1:1). There was a definite commencement to everything (Heb 1:2) but no end (Eph 3:21). The only difference for people is whether they exist in a state of eternal life or death (death is not non-existence but separation from God).

God's next step?

The translation of the Kingdom of God onto the Earth (Rev 1:1; James 5:9). This step is imminent, it could happen at any time (Rev 1:3; Rev 22:7, 12, 20). It is now nearly two thousand years nearer than when this was written. When it occurs this present age will pass away and the day of God's reign on Earth will take over. The Apostle John saw that time (Rev 1:10).

At the centre of eschatology is Jesus Christ and his ultimate triumph over all things (Rev 19:1ff). Notice what the angel says to John (Rev 19:10). All prophecy is bound up in the person of Jesus Christ. He is the Living One, resurrected from death, exalted and alive for ever (Rev 1:12ff). He is King over all kings and Lord over all lords and rulers. He is Lord over his Church (the people called out of this age and committed to him. Not a building, denomination or movement - a people). He is Lord of the nations and will ultimately subdue them (Ps 110:1ff). Eschatology shows Jesus as the 'Lamb of God', the Saviour who redeemed us on the cross (1 Pet 1:20; Rev 5:9f; 13:8).

Why is eschatology important?

It makes us look to the Lord and his word with excitement and anticipation (Rev 1:3). It causes us to assess our lives now in the light of the future (2 Pet 3:11ff). We will all stand before the Judge at the bar of history.