Ephesians 3:9

3:9 and to enlighten everyone about God’s secret plan – a secret that has been hidden for ages in God who has created all things.

Romans 11:25

11:25 For I do not want you to be ignorant of this mystery, brothers and sisters, so that you may not be conceited: A partial hardening has happened to Israel until the full number of the Gentiles has come in.

Romans 16:25

16:25 Now to him who is able to strengthen you according to my gospel and the proclamation of Jesus Christ, according to the revelation of the mystery that had been kept secret for long ages,

Colossians 1:26-27

1:26 that is, the mystery that has been kept hidden from ages and generations, but has now been revealed to his saints. 1:27 God wanted to make known to them the glorious riches of this mystery among the Gentiles, which is Christ in you, the hope of glory.