The question of how Christianity started is a very much open question, as there is NO objective evidence supporting its founding. Since Paul's writings appear to be the first written material for a Jesus of the Bible and were written decades after the supposed events, some Bible scholars (especially the secular ones) support the claim that Paul was the founder of Christianity as we know it today.
Click on the link below for an 18-min video interview with Richard Carrier Ph.D., a noted secular scholar who has devoted his professional life to the study of early Christianity:
How Did Christianity Really Start?
