"The oftener we are mown down by you, the more in number we grow; the blood of Christians is seed." Why Christianity from its inception grew in numbers has remained a relatively stable and uncontested topic. Moreover, recent history has seen a move by some scholars to claim not one but multiple Christianities existed in the first three centuries. No study, however, has approached the growth of Christianity as being a result of positive apologetics and then defended that there was but one Christianity from the beginning through the use of Root Cause Analysis. After proposing an early fixed understanding of those core beliefs that established one as being Christian this study treats the characteristic teachings of Ebionites, Docetists, and Marcionites through the filter of Root Cause Analysis toward supporting the claim that from the origin of Christianity there has been only one Christianity, and that Christianity grew through the use of a positive apologetic.