Note 3 at Col. 1:26: The specific mystery to which Paul is referring is explained in the next verse (see note 5 at v. 27). When he said the mystery had "been hid from ages and from generations," he was speaking about the generations of people under the Old Testament era. They didn't understand the New Covenant mysteries which were prophesied in the Old Covenant because these mysteries could not be understood apart from divine revelation (see notes 4-5 at 1 Cor. 2:9-10, p. 868; see note 3 at 1 Cor. 2:14, p. 869).

But in contrast, the New Testament believer has now had these mysteries made "manifest." The English word "manifest" was translated from the Greek word PHANEROO which means "to render apparent" (Strong). That which was hidden is now made apparent to those who receive the ministry of the Holy Spirit (see note 35 at Jn. 14:26, p. 493).