For the first three hundred years, Christianity was a minority religion on the margins of ancient Roman society. Only half a century later, it was the state religion for a quarter of the world's population. How did this happen, and how should Christians understand this profound shift? In part one of this series, Jonathan and Jacob try to straighten out the history of the first Christian Emperor—Constantine—and lay the foundations for a debate about Christendom, Church, and state which continues to today.  Theme music: © Don Stewart, Recorded/Mixed by Unmuzzled Music Productions.