Man was created to exist forever. He will either exist eternally separated from God by sin, or in union with God through forgiveness and salvation. To be eternally separated from God is Hell. To be eternally in union with Him is eternal life. Heaven and Hell are places of eternal existence.

Scriptures for reference: John 3:16; John 2:25; John 5:11-13; Romans 6:23; Revelation 20:15; 1 John 5:11-12; 
Matthew 25:31-46