Colossians 1:27

To whom God was pleased to make known what is the riches of the glory of this mystery among the Gentiles, which is Christ in you, the hope of the glory.

We heartily agree with Ashby that "There is no need to suppose that Paul borrows this term from the Greek-mystery religions, but rather from the Old Testament (Daniel 2:18)."[56] Also Christ used it himself (see Matthew 13:11).

Christ in you ... This is the essence of the "mystery" as Paul expounded it here; but a comparison with other Pauline writings on the subject reveals the mystery to be somewhat complex. There are eight expressions in the New Testament, all eight of which refer to a single state, namely, the saved state; and these are: (1) Christ is in you; (2) you are in Christ; (3) God is in you; (4) you are in God; (5) the Holy Spirit is in you; (6) you are in the Holy Spirit; (7) the mind of Christ is in you; (8) the word of Christ is in you. For Scriptural references and discussion of all these see Galatians 5:23, this volume. It is mandatory, of course, to see all of these various designations as reference to one condition only, that of the redeemed in Christ. The fact that all such references are indeed synonymous is evident from Paul's usage in this and the following verse. Here he spoke of "Christ in you"; in the very next verse, and speaking of the same thing, he referred to it as presenting every man "in Christ," thus quite obviously using "in Christ" and "Christ in you" interchangeably.