Jerry L. Sumney 
Servants of Satan, False Brothers, and Other Opponents of Paul [PDF ebook] 

This book sets out a method for identifying the opponents in view in Paul’s letters, and then applies it to the relevant writings of the Pauline corpus. The method limits the use of parallels or prior constructions as a basis for identification, dealing with each letter on an individual basis and taking full acount of the historical and social context. Sumney concludes that the Pauline letters address different kinds of opposition in different places, including two distinct anti-Paul movements. Here is a fundamental study for research into a basic problem of the Pauline correspondence.