That's rather novel, NL. At the Final Judgment, the dead are to be resurrected from their graves and given new bodies. At that point, those whom Christ "never knew" are to depart into the lake of fire (prepared for the fallen angels). (cf Matthew 25)
Not only does this mean that they are alive and destined to live eternally deprived of God's presence, but that no one is in heaven or hell as of this time, but rather awaiting the Final (aka Dread) Judgment.
if those cast into hell as you say no longer exist, then how can their greatest punishment in eternity without Christ mean anything?
We didn't exist before we were conceived, and who "remembers" it?