Ephesians 1:9

1:9 He did this when he revealed to us the secret of his will, according to his good pleasure that he set forth in Christ,

Ephesians 3:4

3:4 When reading this, you will be able to understand my insight into this secret of Christ.

Ephesians 5:32

5:32 This mystery is great – but I am actually speaking with reference to Christ and the church.