Sigurd Grindheim, «What the OT Prophets Did Not Know: The Mystery of the Church in Eph 3,2-13», Vol. 84 (2003) 531-553
The purpose of this essay is two-fold. First, it argues that the inclusion of the Gentiles is referred to as a previously unrevealed mystery because it is based upon the abrogation of the Mosaic law and entails a degree of nearness to the Lord that exceeds the expectations of the old covenant. Second, it addresses the question of authorship. Assuming Pauline authorship as a working hypothesis, it shows that the use of the concept of mystery in Eph 3 is intimately linked with Paul’s terminology and thought world attested in the undisputed letters. It is unwarranted, therefore, to find proof of a post-Pauline development in the use of the term "mystery" in Ephesians.
The concept of making the mystery known is introduced in Eph 1,9-10, where the mystery is defined as the summing up of all things in Christ, those in heaven and those on earth15. It is probably best to understand the mystery in ch. 3 as a specific aspect of this, namely the part which deals with the earthly things, which is described here as the bringing together of Jews and Gentiles in unity16. The referent of "as I have previously written to you briefly" must therefore primarily be 2,11-22 and only secondarily 1,9-1017.
The antithesis between the abysmal past of his audience and their glorious presence described in Eph 2,11-22 is well-known from Paul’s