Hell

 There we are warned that it may happen to anyone of us to appear at last before the face of God and hear only the appalling words, ‘I never knew you. Depart from Me.’ In some sense, as dark to the intellect as it is unendurable to the feelings, we can be both banished from the presence of Him who is present everywhere and erased from the knowledge of Him who knows all. We can be left utterly and absolutely outside—repelled, exiled, estranged, finally and unspeakably ignored.

CS Lewis, The Weight of Glory

This is the definition of hell.  The bible describes hell as a place of fire.  I think this is one of the few ways in which God can convey to us mere mortals a place where He does not exist.  A place of eternal torment.  

Most of us have probably burned ourselves at one point or another in our lives.  It is painful, and it is a pain that continues to linger.  Burned skin hurts when it is burning, and it hurts for days afterwards until it is healed.  It is a pain like no other.

But Hell is a place a place where there is no God.  We will know He exists. We will know what we missed, but like a burn, it will linger and linger.  It will never heal.  We will always know what could have been, but we will never be able to experience.  For our actions here on this earth will have doomed us to a place where when we have finally rejected God for the last time, we will know what might have been.  And we will suffer for ever due to our actions.