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.

Ephesians 3:3-4

3:3 that by revelation the divine secret was made known to me, as I wrote before briefly. 3:4 When reading this, you will be able to understand my insight into this secret of Christ.

Ephesians 5:12

5:12 For the things they do in secret are shameful even to mention.