“The community that confesses that Jesus is Lord has been, from the very beginning, a movement launched into the public life of mankind. The Greco-Roman world in which the New Testament was written was full of societies offering to those who wished to join a way of personal salvation through religious teaching and practice. There were several commonly used Greek words for such societies. At no time did the church use any of these names for itself. It was not, and could not be, a society offering personal salvation for those who cared to avail themselves of it teaching and practice. It was from the beginning a movement claiming the allegiance of all peoples, and it used for itself with almost totally consistency the name ecclesia – the assembly of all citizens called to deal with the public affairs of the city…the church could have escaped persecution by the Roman Empire if it had been content to be treated as a “cultus privatus” – one of the many forms of personal religion. But it was not. Its affirmation that “Jesus is Lord” implied a public, universal claim that was bound to eventually clash with the cultus publicus of the empire…”
Lesslie Newbigin in The Open Secret