Enoch walked faithfully with God; then he was no more, because God took him away.
Genesis 5:24 (NIV)
Some believe in the "Rapture," a future event where God will simply whoosh Christian believers away into heaven before the "Great Tribulation," where God's judgement is poured out like liquid from a bowl that floods the world in God's wrath.
They look at Enoch as an example, who is also taken up.
This does make some of us wonder why Noah, who was called "righteous in his generation" was not taken into heaven like Enoch.