Judgement of Light was the attack which can only be used by the priest who was a follower of the Goddess Rebecca.
It inflicts heart-wrenching pain on those who have been corrupted or when punished.
But more than that it had another use which is to undermine superiority.
If two people were to fight with one another and they are asked to use the Judgement of Light then one who had higher faith and belief or is blessed by Goddess herself cannot be harmed by the one who had less belief.
In a way, Alex is resistant to any attack cast by the follower Goddess Rebecca because the attacks mostly relied on faith more than one's mana.
But this case is only true for Goddess Rebecca, not for others. If you applied this logic in front of Goddess Of War followers you are just giving away your head and body to them freely, to be cut and shredded into pieces.
