Armageddon is terrifying for believers and refers to an imagined battle between Christ and the Antichrist though the word Armageddon often describes the whole end times scenario rather than just the battle.
What'll happen is that the sun and moon will become dark and stars will fall from the sky. The Iron Age people who wrote the New Testament presumably believed the stars were something small that could fall in large numbers. Then Jesus will turn up coming down from the sky with a great fanfare of trumpets. At some stage, those God has chosen will magically float up into the sky, the dead will rise from their graves and the living will just rise. Christians can’t agree exactly when this will happen.  Meanwhile the world will suffer through catastrophes, such as meteorites, and have the sea turn into blood, with all the nonbelievers in it. George Bernard Shaw described the whole nonsense as "a curious record of the visions of a drug addict" 
And don’t forget that God loves us.
This was probably made to scare credulous folk into believing their religion.
End of the world scares happen continually, the last major scare before 2012 was round the year 2000 though there was a smaller scare in 2008 and minor scares affect small numbers of believers at least once most years. The last major scare was towards the end of 2012.
- Revelation's Place in the Christian Bible (2007)
- Rapture & Armageddon
- "The end of the world as we know it" prophecies