User blog comment:Nekokokokoko/Slane Theocracy's awareness of Ainz/@comment-80.213.121.95-20150919153419/@comment-173.174.147.126-20150920161649

They first became aware of Ainz after the battle of Carne village. some of the Knights who faced off against the Death knight were allowed to live for the very reason of telling their masters about Ainz and the threat he made to them should they return.

The fact that the sunlight scripture didn't return against their fight with Gazef would have seemed impossible. when combined with the surviving Knights report, it became obvious what had happened.

At this point, Slane Theocracy knows Ainz's strength is at least enough to control a Death knight and more probable, he can defeat an Angel capable of beating a god.

Gazef believes there is a spy for Slane Theocracy in the nobles of the Kingdom. This would confirm the existence of Ainz to the Theocracy. Any info gathered about Ainz from rezzing wouldn't expand their knowledge on his power but it would let them know his is Momon.

Everything after that is speculation. They know he's dangerous enough that for the first time, they proclaim neutrality in the upcoming war.