Manichaeism was quickly successful and spread far through the Aramaic-speaking regions. It thrived between the third and seventh centuries, and at its height was one of the most widespread religions in the world. Manichaean churches and scriptures existed as far east as China and as far west as the Roman Empire. It was briefly the main rival to Christianity before the spread of Islam in the competition to replace classical paganism. Manichaeism survived longer in the east than in the west, and it appears to have finally faded away after the 14th century in south China, contemporary to the decline of the Church of the East in Ming China. While most of Manichaeism's original writings have been lost, numerous translations and fragmentary texts have survived.
An adherent of Manichaeism is called a Manichaean or Manichean, or Manichee, especially in older sources.”
This is from [en.m.wikipedia.org]
I think that most spiritual people ever made such hard and fast distinctions. However, if you real literature from this period m you will find this a common belief. Common but never universal. You have to look at each individual writing to determine whether it contained this outlook.
This notion had other sources than Mani’s movement. Attitudes were present in a Greek though through Pythagoras and, even parts of Plato. It was kind of an elitist view IMO, rejected by most normal human beings. Hope this helps.