The answer
First: They are deprived of divine grace. They receive retribution according to their stubborn hearts, and so they will not see God in his glory.
Second: Their heart is afflicted with the worm that does not die, which means that sorrow and bitterness over their deeds will not depart from them.
Third: They have fellowship with the devil and dark forces in the lake of fire that never goes out.
Fourth: We hear of Hades and the torment (Luke 16:23) that no one can comprehend.
Fr. Tadros Yacoub Malaty