The growth of the early church was amazingly quick
At the time of the first Easter there were perhaps a score of people who believed that Jesus had risen from the dead, either because they had met the risen Jesus or had been told by their companions. These people were “working class” and generally uneducated and who lived in an obscure corner of the Roman Empire. Not the sort of people who would have great influence or even be noticed.
However, by 300AD, there were 3 million believers throughout the Roman Empire and by 400AD, after the conversion of Emperor Constantine, there were 300 million - about half the population of the Empire. At about this time, Christianity became the official religion of the Empire.
Much of the explosive growth at the beginning took place in the face of persecution, from the Jews, who took exception to Jesus being acclaimed as their Messiah, from the commercial interests whose trade would take a hit if people stopped worshipping the pagan gods, and eventually from the Romans who declared the religion illegal.
In these days there are 2 billion Christians worldwide, about a quarter of the world’s population.
Even historians who are devout atheists, acknowledge this. For instance Bart Ehrman, who wrote a book called “The Triumph of Christianity” affirms this as a historical fact even though he doesn’t believe that Jesus is who Christians say that He is.
What could explain such a phenomenon? While nothing can be proved, it seems probable that this is what God intended.