Romans 16:25 Now to Him who is able to establish you according to my gospel and the preaching of Jesus Christ, according to the revelation of the mystery which has been kept secret for long ages past,

Ephesians 3:3 that by revelation there was made known to me the mystery, as I wrote before in brief.

Colossians 2:2 that their hearts may be encouraged, having been knit together in love, and attaining to all the wealth that comes from the full assurance of understanding, resulting in a true knowledge of God's mystery, that is, Christ Himself,

Colossians 4:3 praying at the same time for us as well, that God will open up to us a door for the word, so that we may speak forth the mystery of Christ, for which I have also been imprisoned; (NASB ©1995)