Thoughts from a short book I read published by Day One.
The conditions were good for the start of Christianity. The Greeks had spread their culture, and consequently language, far and wide throughout the Mediterranean. This meant only one language was really needed to communicate with people everywhere the early Christians went. The Romans had clamped down on Piracy (Pompeii in particular) and bandits, and made a vast network of good straight roads. This enabled relatively safe and speedy travel. Finally, the Jewish Diaspora had resulted in many Jewish communities in all the main towns and cities. There were also many God Fearers – those from pagan background interested in a religion with superior morals and one God. This meant those that spread Christianity had communities to preach to throughout the Roman world.
Morality in the Roman empire was dreadful with orgies, drunkenness, temple prostitutes etc. Christianity, and Judaism too, offered a fresh moral direction.
The early Christians were committed to helping the poor, those in prison, and held hostage. Money was often given by selling possessions or selling church silver or gold plates etc.