Almost anything by Robert Wilken is worth reading. I have benefitted immensely from his The Spirit of Early Christian Thought (Yale University Press, 2003) and The First Thousand Years: A Global History of Christianity (Yale University Press, 2012). Wilken does not disappoint in his most recent book, Liberty in the Things of God: The Christian Origins of Religious Freedom (Yale University Press, 2019).
Early on Wilken offers the following quote: "It is only right . . . that every person should be able to worship according to his own convictions. For one person's religion neither harms nor hurts another."