I think the 'universal appeal' of Paul's message was that it was egalitarian. You didn't have to be of a social elite. You didn't have to be one of the initiated. You didn't have to be from a certain bloodline. Any Joe on the street could attain this eternal life. If he claimed that most people would still go to hell, it wasn't because they didn't have the option of salvation, but that they chose not to take it.

Most other contemporary religions catered to exclusive groups, kind of like country clubs today. Christianity would accept anyone and give them a reason to feel proud and beloved that no one else would extend them.

Ajax