To address the readers as “the twelve tribes scattered among the nations” immediately identifies them as people for whom the OT has meaning. Scholars are agreed that the epistle exhibits a Jewish milieu. Probably the accustomed meeting place for the readers was the synagogue. (The NIV leaves this matter open by translating the Greek word synagōgē as “meeting” in 2:2.)
Most striking about the epistle, furthermore, is the want of distinctively Christian features. “Except for two or three references to Christ, it would fit rather well in the OT. The life to which the epistle exhorts is that of a profoundly pious Jew who is fulfilling the law in every regard. Gospel, redemption, incarnation and resurrection are not mentioned” (Dayton, ZPEB, 3:396). By the same token, large segments of OT Wisdom literature lack evidence of Israelite tradition.