How does The Agnostic work??

I'm trying to copy a coc ice spear/nova build from poe ninja


I realised a lot of low life occultists took The Agnostic.


How does that work??

I understand this skill will set your ES to 0, wouldn't that mean you die really easily since your life is already low in the first place


Am i missing anything? I thought this skill would be more useful for high hp and mana builds instead.

Thanks!!

They use Militant Faith jewel to transform Agnostic into Inner Conviction (gain power charges instead of frenzy charges, and more spell dmg per power charge).