Zhou Ping'an started from the beginning.
The cultivation path he chose was the orthodox one of refining blood into Qi, opening up the body's meridians, achieving unity with heaven and man, and then comprehending the rules of the world.
Plainly speaking, it was the Daoist cultivation method passed down from the Cloud Water Sect of Another World.
Latter on, due to a series of fortunate mishaps, he started practicing a Demonic body tempering technique and, by a stroke of fate, acquired the "Five Desires Evil Art," progressing rapidly. He then glimpsed at the Supreme Devils Scripture, the "Prison Suppressing Demon Subjugation," and from then on, he was walking on two paths.
Perhaps, from the perspective of Another World, Daoism and Demonic cultivation are incompatible. If one cultivates one, they would scorn the other. In fact, once it is known that a disciple is practicing a heterodox technique, they would likely be condemned and attacked in public, if not dealt with secretly.