Zhou Tian seeing through the identities of those deities was not particularly surprising, given that the other party had exposed numerous 'weaknesses.'
First of all, if the other party really were deities under a Divine King, how could they possibly be so easygoing right now? Given their faction's power, if Zhou Tian truly intruded into their territory and the Divine King disapproved of deities allowing such actions, then unless Zhou Tian possessed overwhelming divine strength or had the protection of other deities, it is likely that the moment he entered their territory, he would immediately face attacks from the Divine King's subordinate deities. No matter how one viewed the situation, true subordinates of a Divine King would never behave as accommodatingly as they currently were after Zhou Tian trespassed into their territory.
Moreover, the strength of those deities was another reason for their identities being exposed.