The demise of "Christendom" affects both the Church's theological dialogue and missional strategy.
Michael Frost and Alan Hirsch give the historical explanation for what it is:
Christendom is the name given to the sacral culture that has dominated European society from around the eleventh century until the end of the twentieth. Its sources go to a time when Constantine came to the throne of the Roman Empire and granted Christians complete freedom of worship and even favored Christianity, thereby undermining all other religions in the empire. . .
Taken as a sociopolitical reality, Christendom has been in decline for the last 250 years, so much so that contemporary Western culture has bee…