The believer may experience a temporary hell for a thousand years during the time of the kingdom if they will not live obediently. They aren't foolish virgins for not believing (that is still how to be saved, right?} They are foolish for thinking that once they were saved that they would not be accountable to their Lord who shed His own blood to save them from the eternal death in the lake of fire. So they decided to live for this world instead of getting ready for the next.
Matthew 16:24-26
24 Then said Jesus unto his disciples, If any man will come after me, let him deny himself, and take up his cross, and follow me.
25 For whosoever will save his life shall lose it: and whosoever will lose his life for my sake shall find it.
26 For what is a man profited, if he shall gain the whole world, and lose his own soul? or what shall a man give in exchange for his soul?
The salvation of the soul during the millennium age is based upon obedience, losing our lives in this age that we may find it in the next. If we will deny our Lord, He will deny us. The foolish virgins, the wicked slothful servant, they are all the disobedient believer who rises up to play in the face of every warning that God has given.