Although eschatology isn’t found in the Bible, it does refer to a biblical concept: the end of the world, sometimes called the end times. Eschatology, then is the study and theology of the end of the world as we know it.
The primary book in the Bible to addresses this is Revelation, though other books also contain passages or sections that cover this topic. The last half of Daniel is a key example. The gospels of Matthew, Mark, and Luke all contain an end time teaching as well (Matthew 21, Mark 13, and Luke 21).
Some people read the book of Revelation as a literal account of what will actually happen at the end of the world. Others understand it from a figurative perspective: a great supernatural battle will occur, evil will be defeated, and those who follow Jesus will join him in a new existence (that is, heaven).
Apocalypse can generically refer to any prediction or prophecy about the future destruction of the world, that is, the end times. In a general sense, an apocalypse can refer to any prophecy or revelation. Two books in the Bible align with this perspective and are called Apocalyptic books. They are Daniel and Revelation.
Jesus says nobody knows when the world will end. Later on Paul confirms no one knows when Jesus will return (therefore signaling the start of the end). It will happen unexpectedly, like a “thief in the night.”
So if the Bible says no one knows, why do some preachers make their audacious predictions anyway? Adding to their error, they often tap the Bible for clues as to when, even though the Bible says no one knows. Yet they try anyway. I’m not sure if this is out of arrogance of who they are or ignorance over what the Bible says.
Yes, we need to be ready, but we don’t know when the end will occur. So let’s forget about trying to figure out what we can’t know and instead focus on doing what we already do know, the things Jesus told us to do.
After all, be it far away or near, the end will happen when it happens.