Like James, Peter’s first letter appears to reflect a Jewish Christianity. Surprisingly, this is not the majority opinion. In his brief notes on 1 Peter in the ESV Study Bible, Thomas Schriener comments that “Most scholars are convinced that the recipients of 1 Peter were primarily Gentiles” (ESVSB 2402). Carson and Moo (Introduction, 647) assume a mixed congregation. Raymond Brown (Introduction, 720) also sees the target audience of 1 Peter as “Gentiles who have been heavily catechized with a strong appreciation of Judaism.”
There are several indications that Peter is addressed to Jewish Christians congregations, which may include God-Fearing Gentile converts, but I would prefer to see these primarily Jewish Christian churches.
1 Peter 1:1 addresses “the elect” who are “scatted” (1:1, NIV). Both words are significant in that they point to a Jewish audience. The “Elect” is a common self-designation in Judaism. They are the nation which God chose (via Abraham, or in the prophets, when he rescued the nation out of Egypt). “Scattered” is the Greek diaspora, the Diaspora. This was a word used frequently to describe Jews loving outside of the Land, including those regions addressed in 1 Peter 1:1.
These elect believers are described as being in exile (ESV). This word is better translated as “sojourners,” or “strangers.” The Greek parepidamos is rare in the New Testament, occurring here, 2:11 and Heb 11:13 referring to the children of Abraham (LXX Gen 23:24, LXX PS 38:13, 39:12 ET). The synonym paroikos appears in Acts 7:6 with a similar sense.
If one sees the addressees of 1 Peter as Gentile, then these descriptions must be taken as metaphors. It is assumed that the church is New Israel, and so Christians like Peter picked up on language once applied to the Jewish Diaspora and re-apply it spiritually to the Church (as Schreiner does in ESVSB 2405). If Peter, like James, is writing a letter to other Diaspora Jews, then there is no reason to take the language referring to anything other than Jewish believers.
There are several other examples of letters to Jews in the Diaspora. In Jer 29:4-23 a letter is sent to Jews living in Babylon. Similarly, 2 Baruch 78-87 imagines a similar letter sent from Baruch after the fall of Jerusalem. The first chapter of 2 Maccabees is a letter sent to Alexandrian Jews. James should also be included in this list, as well as the book of Hebrews, which is addressed to Jews living in Rome in the mid first century, although the word Diaspora does not appear there. It is therefore Peter stands in a tradition of Jewish writers and leaders writing to Jews in the Hellenistic world to encourage them in their belief and practice.
I suppose that we can revisit the question of a few days ago – is there anything in the letter (or in history, tradition, etc.) that makes us think Peter actually visited congregations in these regions? Since we know little of Peter’s ministry after Acts 12, it is hard to be dogmatic.