John Gresham Machen 
The Origin of Paul’s Religion [EPUB ebook] 

The Origin of Paul’s Religion is intended to deal, from one particular point of view, with the problem of the origin of Christianity. It is an important historical problem not only because of the large place which Christianity has occupied in the medieval and modern world, but also because of certain unique features which even the most unsympathetic and superficial examination must detect in the beginnings of the Christian movement. The problem of the origin of Christianity is also an important practical problem. Rightly or wrongly, Christian experience has ordinarily been connected with one particular view of the origin of the Christian movement; where that view has been abandoned, the experience has ceased.