The church that is at Babylon, elected together with you, saluteth you; and so doth Marcus my son. (1 Pet 5:13)
Some critics of Petrine authorship of 1 Peter argue that the text must have been written post-70 as it would not have made sense for a pre-70 text to use "Babylon" as a cipher for Rome as such is believed to be a post-70 phenomenon in Jewish apocalyptic literature.
Liberal New Testament scholar Markus Bockmuehl offered the following refutation of such an argument:
[T]he use of Babylon as a cipher for Rome does in fact pre-date the year AD 70. Jewish reapplication to the second temple of prophecies about Babylon’s destruction of the first temple is well attested since at least Dan. 9 and appears to feature in Jesus’s predictions of the temple’s destruction (e.g, Mark 13:14). Josephus likewise believed Jeremiah to be speaking about the year 70 (Ant. 10.79), while Yohanan ben Zakkai was said to have attributed to the prophecy of Jerusalem’s fall to Isa. 10:34 (‘Abot de Rabbi Nathan A 4.41ff.). As early as Dan. 11:30 one encounters the identification of the “Kittim” with the Romans (explicitly so in the case of the Septuagint and several other ancient versions), an interpretation that is also common in the Dead Sea Scrolls, where additional links with Assyrian/Babylonia are also found (cf. 4Q163 [Isaiah pesher] frag. 4 7.ii 1-4, frag. 8 10.1; 4Q554 frag. 3 iii.14-22). In the first century AD, the Sibylline Oracles lumps together “Babylon and the land of Italy” (5.159-60; cf. 168-70; cf. also the Christian text 4 Ezra [= 2 Esdras/6 Ezra] 15.46-48). (Markus Bockmuehl, Simon Peter in Scripture and Memory: The New Testament Apostle in the Early Church [Grand Rapids, Mich.: Baker Academic, 2012], 128)