“The church in Babylon... sends you greetings”
The church in Babylon, chosen together with you, sends you greetings, as does my son Mark. (1 Peter 5:13 BSB)
What it sounds like today
A greeting from Mesopotamia.
The cultural key
Almost certainly not the literal Babylon, by then a backwater. 'Babylon' was live Jewish code for Rome: the empire that destroyed the temple as Babylon had, a cipher used in Revelation ('Babylon the great') and in Jewish apocalypses of the era. 'She' is the church there ('likewise chosen'). The greeting quietly matches the old tradition that Peter ended in Rome with Mark beside him, the Mark whose Gospel tradition calls the record of Peter's preaching (see the Mark cards' eyewitness touches).
Recovered meaning
A coded return address: the church in the new Babylon greets the scattered exiles, one displaced community to another. The cipher itself is theology: whatever empire hosts you, the people of God write from Babylon and live by another city's law.