Ephesians 3:8-11

What Paul is suggesting here, really, it is more than a suggestion, he is telling us outright, that the unfolding of God's plan in the church is a revelation to angels as well. They were not exactly sure how all this was going to work out, but they had to wait until it was revealed through Jesus Christ in this time. So the mystery of God's grace and His plan of redemption was hidden even from them, who play such an important part in the plan of God, especially toward us, because they are God's servants to minister to those who are now seeking salvation. And just to add this here, in Matthew 24:36 in the Sermon on the Mount, Jesus says that even the angels do not know when He will return. Only the Father.