Of the twenty-one epistles in the New Testament, five were written to Jewish believers dealing with their specific needs and issues in mind. There are things in these epistles applicable to all believers, but some are true only of Jewish believers. The epistles are Hebrews, James, I & II Peter, and Jude.
The first century Messianic Jewish community was faced with two major problems: persecution and false doctrine.
To deal with the first problem of persecution, Hebrews, James, and I Peter were written. Persecution took place both within the Land of Israel and among the Jewish believers of the Diaspora, Diaspora - being a technical term for Jews living outside the Land of Israel (e.g., James 1:1; I Peter 1:1). The book of Hebrews was written from within the Diaspora in order to deal with the persecution of Jewish believers in the Land of Israel. The epistles of James and I Peter were written in order to deal with the persecution of Jewish believers in the Diaspora; James written from within the Land of Israel, and I Peter written from within the Diaspora itself.
To deal with the second problem of false doctrine, two other epistles were written: II Peter and Jude. Second Peter was written from one part of the Diaspora to Jewish believers in another part of the Diaspora. Jude was written from within the Land of Israel to Jewish believers in the Diaspora.