The Mysteries of the New Covenant
Jesus coming in the flesh, dying and resurrecting from the dead ushered in a new age. God made know the mysteries that were previously hidden within the old covenant.
Colossians 1:25-27 I have become its servant by the commission God gave me to present to you the word of God in its fullness— 26 the mystery that has been kept hidden for ages and generations, but is now disclosed to the Lord’s people. 27 To them God has chosen to make known among the Gentiles the glorious riches of this mystery, which is Christ in you, the hope of glory.
The mystery is Christ is in you, the hope of glory. This mystery has opened the flood gates of wisdom that was hidden within the old covenant.
The Mystery of Spiritual Warfare
Hebrews 10:1 The law is only a shadow of the good things that are coming—not the realities themselves.
For this reason the battle is now not against flesh and blood but rather against principalities and powers. In the old testament the war was a battle against flesh and blood and the redemptive power of Christ was not in effect the way it is now.
In the old testiment God ordered His people to wipe out the 7 tribes in Cannan. Even the women and children. But now God does not order such commands and saves them through Jesus.
The 7 tribes in cannan each represent a specific principality rather than a group of people. As you look at the Hebrew language you will get a detailed insight how each principality works. This is a mystery that Jesus has unlocked for New Covenant believers.