From long ago until today, it is not rare to see "mainstream" Daoist traditions (Orthodox Unity Zhengyi 正一)distinguished from local ritual traditions that give precedence to excorcism(Lüshan 閭山 or Sannai 三奶)based on ideas of orthodoxy and heterodoxy. However, the notion of this differentiation is not so absolute. This paper discusses the tradition of Daofa ermen that spread to northern Taiwan from its place of origin in the Hakka region of Zhao’an County, Fujian. The changes that appeared in its historical development serve as the scope of the paper. An examination of the origins of northern Taiwan’s Daofa ermen tradition will assist us in recognizing how a local Daoist tradition interprets this differentiation between orthodoxy and heterodoxy, as well as the dialectical process in the convergence of Dao and Fa.