Some people are accustomed to the sunlight, while others have no idea how to live once touched by the sun.
Sun Yi was not an exception in the Blood Feast, but rather the majority.
Accustomed to massacre and "Blood Food" after, their attitude towards other Mortals had completely changed.
"Would you show respect to milk and bread running all over the street?"
You wouldn't, and naturally, neither would they.
They no longer saw themselves as the same kind, and after mingling in the Blood Feast for so long, they essentially regarded themselves as a "superior Species," a born Predator destined for superiority.
On the one hand, this was the influence of the twisted values within the Evil God Church; on the other hand, it was because "Power" and "Knowledge" are inherently toxic.
Power contains the will of the superiors, while Knowledge is steeped in specific rules and values.