Quote from A Course in Miracles Text Chapter 8 - THE JOURNEY BACK.

T-8.III.3. The Will of the Father and of the Son are One, by Their extension. 2 Their extension is the result of Their Oneness, holding Their unity together by extending Their joint Will. 3 This is perfect creation by the perfectly created, in union with the perfect Creator. 4 The Father must give fatherhood to His Son, because His Own Fatherhood must be extended outward. 5 You who belong in God have the holy function of extending His Fatherhood by placing no limits upon it. 6 Let the Holy Spirit teach you how to do this, for you can know what it means only of God Himself.