Christians claim the existence of the church today, still, after so long is evidence that their god is the true god.
Above is a link I found helpful in understanding the success of Christianity, both fundamentalist and liberal versions.
The reason is the human and humane qualities Christianity espouses in building community and meeting fundamental needs of people in that day.
Christianity was Socialism at its finest back in the early days. The members helped each other when in need, including supporting widows. The religion aspect appealed to downtrodden people who saw no hope for a good life, so the Christian Churches started preaching eternal salvation, sitting on clouds playing a harp to show how grateful you are to this capital “G” god who put you in the predicament in the first place. The early Christians also provided education to everyone and started universities. Constantine made Christianity an official religion of the Roman Empire out of political necessity.
As the Christian religion grew and its power coalesced in Rome the Catholic Church became one of the most powerful military and political institutions in the world. With power comes corruption, but the subject in this thread stops before we get there. The essays are a fairly long read, but I played some jazz at low volume on my office stereo and read through them in less than 45 minutes total spread over three hours. The first essay is poorly written. Slog through it or skip it, but it does set the tone for the following articles. Although the authors emphasize different areas that led to Christianity’s survival they all mention community as one of the most important factors. Christians welcomed outsiders back then and gave them equal status immediately, with access to full public benefits.
That’s what I got from the authors, and it makes sense. Thanks for the link.