Colossians 1:27

That God would save Gentiles was no new revelation (e.g., Isaiah 49:6), but that He would dwell in them and deal with them on the same basis as He did Jews was new revelation. Those who rejected this revelation insisted that Gentiles had to become Jews before they could become Christians (cf. Acts 15:1).

"At least four defining characteristics of the church are described as a mystery. (1) The body concept of Jewish and Gentile believers united into one body is designated as a mystery in Ephesians 3:1-12. (2) The doctrine of Christ indwelling every believer, the Christ-in-you concept, is called a mystery in Colossians 1:24-27 (cf. Colossians 2:10-19; Colossians 3:4; Colossians 3:11). (3) The church as the Bride of Christ is called a mystery in Ephesians 5:22-32. (4) The Rapture is called a mystery in 1 Corinthians 15:50-58. These four mysteries describe qualities that distinguish the church from Israel." [Note: Arnold G. Fruchtenbaum, "Israel and the Church," in Issues in Dispensationalism, pp. 117-18.]

Progressive dispensationalists, along with non-dispensationalists (i.e., covenant theologians), interpret the mystery of Christ in us as the realization of the Old Testament promise that God would put His Spirit within believers (Ezekiel 36:27; cf. Ezekiel 37:14). [Note: See Saucy, The Case . . ., pp. 167-73.] Normative dispensationalists take this mystery as new revelation that Christ would indwell believers in the church. [Note: Charles C. Ryrie, Dispensationalism Today, p. 135; idem, Dispensationalism, pp. 124-25; Wiersbe, 2:122.] The difference is not in the Spirit and Christ distinction; both positions see unity between the Spirit and Christ. The difference is the concept of the church, though both progressive and normative dispensationalists see the church as distinct from Israel. Progressives view the church as the present predicted phase of the messianic (Davidic) kingdom. Normatives see the church as distinct from the messianic (Davidic) kingdom and not predicted in the Old Testament.

"It is striking that for the third time in these opening paragraphs the theme of hope is given central place in the gospel (Colossians 1:5; Colossians 1:23; Colossians 1:27 . . .). This is an appropriate note on which to wind up this brief reference to the mystery of God’s purpose shaped from before the ages and generations and now moving toward its eschatological climax." [Note: Dunn, p. 123.]