Perfect Justice in Judgment (in Gehenna, Hell or Lake of Fire):

“Woe to the wicked–it will go badly for them, for what they have done will be done to them.” (Isaiah 3:11)

Not forever but till “Mercy triumphs over judgment” as it is also written that:

“For judgment is without mercy to one who has shown no mercy. Mercy triumphs over judgment.” (James 2:13)

P/S:

Hell perfectly serves out the Justice of God for one is only meted out punishments which are same and according to what they have done; one is never punished with a more cruel punishment than what one has done but neither it is forever due to God’s Mercy triumphing over all judgment as verses reveal.

“My heavenly Father will also do the same to you, if each of you does not forgive his brother from your heart.” – Lord Jesus Christ (Matthew 18:35)

“In everything, therefore, treat people the same way you want them to treat you, for this is the Law and the Prophets.” – Lord Jesus Christ (Matthew 7:12)