This lesson talks about Christianity transforming from an underground religion to widespread. This would be a massive change since the standard for religions is that "everyone can have their own god" and that there are multiple gods. Christianity would make a change with the stance that the Christian God cannot be compared to the pagan gods, and in fact he is the only 1 true God.
A Roman general conducted an experiment where he interviewed people from Rome. He asked whether they were Christian or not. The ones who said they were he ordered executed, the one's who denied they were he let go, and the ones who said they were Christian but were Roman citizens he transported out of Rome.
He interrogated some of the self proclaimed Christians, and they told him their traditions which consisted of collective prayers, praising, hymn singing, etc.