BOOK: The Person and Ministry of the Holy Spirit
Chapter 1.3: Plan of the Ages

1.3    Plan of the Ages

God formed a plan, the Plan of the Ages, before anything was created.  God the Father formed a plan and presented it to the Son and Spirit, because what ever They do, they do in total agreement and covenant.  Proof of plan:
Rev  4:11 all things created for His pleasure
1 Peter 1:18-20 Jesus crucified before foundations of the world
Prov 16:4 God has made all things for Himself
A plan that was hidden in the old testament, that even the angels did not know about:
1 Pet 1:9-12 ~ prophets trying to tell time, angels desire to see
Eph  3:9-11 ~ hid, according to the eternal purpose, in Christ
For what purpose:
Eph        1:4-6
According as he hath chosen us in him before the foundation of the world, that we should be holy and without blame before him in love: Having predestinated us unto the adoption of children by Jesus Christ to himself, according to the good pleasure of his will, To the praise of the glory of his grace, wherein he hath made us accepted in the beloved.       
Eph 1:11-12
In whom also we have obtained an inheritance, being predestinated according to the purpose of him who worketh all things after the counsel of his own will: That we should be to the praise of his glory, who first trusted in Christ.
There were several purposes.  For God's pleasure thru His good purpose.  For God's glory.             
Eph 3:21
Unto him be glory in the church by Christ Jesus throughout all ages, world without end. Amen.
But God the Father is not a selfish God.  He seeks to bless. 
As a loving Father, He sought to leave His Son an inheritance.  As a mature Father, He sought to have His Son grow up and subdue it Himself.          
Colos 1:18 -19
And he is the head of the body, the church: who is the beginning, the firstborn from the dead; that in all things he might have the preeminence. For it pleased the Father that in him should all fulness dwell;
So the Plan of the Ages was for the Son's sake, to the glory of God.  This included the fall of angels, of man, and the crucifixion and resurrection of Jesus.  So that we might be brothers of Jesus Christ, going thru the cross with Him, unto His glory and reign.  Praise God forever more!