Been reading Tom Wright’s commentary of John’s Gospel. Just got to his section on John 3:14-21 and found this covering his view on God’s judgement. He says,
‘The darkness (and those who embrace it) must be condemned, not because it offends against some arbitrary laws which God made up for the fun of it, and certainly not because it has to do with the material, created world rather than with a supposed ‘spiritual’ world. It must be condemned because evil is destroying and defacing the present world, and preventing people coming forward into God’s new world’
I think this encapsulates why there will be judgement, but how God’s judgement is constructive unlike so much human judgement which is destructive, a seeking after revenge for the sake of getting even in some way.