Renji had always been a man of action. From the moment he arrived at the Ancient Wolf clan, he had a faint sense that there was hidden impurity lurking in the depths here. This impurity was like a radar for detecting tainted miasma, a power that came with being the "main character."
This feeling became even more pronounced as the High Priestess danced on the stage, spreading impurity and sending the demi-humans below into a fanatical frenzy. When the High Priestess shed blood to weaken the curse for the demi-humans, Renji was certain that the High Priestess and the deep-seated impurity he sensed were of the same origin.
So, the entire plan had been set up from the very beginning by Renji. This included his decision to use a tone of 'unfamiliarity' and 'doubt' when he blatantly asked the question, -"Who are you?"- – a question that could undoubtedly cause significant harm.