The outward effects of Sky Devil Sect's cultivation technique could scare people to death and it was difficult to conceal. This had been one of Ji Changsheng's greatest headaches in the past during his transformation.
After all, he was of the Illusory Light lineage and had access to various illusions, unlike the other disciples of the Sky Devil Sect. No matter how these disciples of the Sky Devil Sect referred to themselves as the Holy Sect in their daily lives, once they showed their hands, they would undoubtedly expose that they were indeed children of the devil.
However, Ji Changsheng later realised that since he couldn't change the explosive reality of the Sky Devil Sect's cultivation technique, then he would change the way people perceive it.
A fact is a fact, but the interpretation of that fact can be manipulated.
Who could definitively say that a rat is a rat? To him, it looked quite like a duck.