The BBC has put out a little series: Why Didn't Christianity Die Out in the 1st C CE? Much of it is focused on the work of Professor Kate Cooper of the University of Manchester. Her most recent book Band of Angels: The Forgotten World of Early Christian Women, suggests that small networks of Jesus followers, particularly women meeting in small gatherings and houses, helped spread the gospel. From the publication details above, it's clear that the book has traction and has been well received. I'm going to review this work soon for BAR so more soon.