Firstly I hope you don't need to see this in order to ptogress in the game, but if this helps you out, or you just want to know for sure, here's the answer.
When chasing Panghast's assasin, you *need* to go to the shrine of the priestess, she'll inform you on how to free a god from their deal.
Then, when the assasin tells you to kill him, offer to free him instead, he will accept and will join your journey.
When in your temple, mingle at the grand hall. He'll tell you that he still feels Panghast's influence and that you should destroy certain statues, and will give you their overal location. They're pretty easy to find, whenever you enter a place and see soemthing along the lines of "you feel yourself being watched", or "the statue is far away-", you will gain the option to destroy them.