Phyzy: Why did it appeal so ? I think it was Paul's "There is neither Jew nor Greek, there is neither slave nor freeman, there is neither male nor female, for you are all one in Christ Jesus" that struck a chord with the common person.
Yes, indeed, Paul's rhetoric was attractive for the masses. It was indeed attractive for me for many years. However, even Paul was deceived by the idea of the return of Jesus, which did not happen. In fact, Paul's thinking was revolutionary for that time, when people were wasting time and money in pagan cults. Without Paul, christianity could not have improved. Today, we know the fiasco of the christian religion, but it was an interesting phenomena in the first century.