Apparently, even non-Buddhist practitioners with some spiritual realization may still be confused about the workings of cause and effect, not to mention people without any right view or understanding. These non-Buddhist practitioners are usually well learned; some may even have acquired certain clairvoyance over worldly matters. However, they jumped to a conclusion only based upon what they saw—virtuous people took rebirth in the lower realms—and from it the conclusion was drawn that cause and effect could not have existed. Then books were written and theories developed based on this conclusion, which gradually formed into a sect after attracting enough followers. This is how nihilism was established.
~ Depicted from Luminous Wisdom Book Series 1