The Words of Sun Myung Moon from 1972
We cannot surpass the fallen world until we establish complete unity between Cain and Abel. According to the Principle, only when we establish the Foundation of Substance can we go beyond the realm of the fallen world for the first time.
You might be able to go beyond the fallen world up to the level of the Formation or even the Growth Stage, but you cannot advance further than the Growth Stage unless you establish a victorious Foundation of Substance. Even if you could enter the level of Perfection, your lineage would not yet have been cleansed. Since the satanic blood lineage has been inherited and that lineage is not yet cleansed, you need the Messiah. Therefore, it is absolutely necessary for fallen people to establish the Foundation of Faith and the Foundation of Substance as the Foundation to receive the Messiah. Only through the Messiah are you able to change your blood lineage and stand in the position of a true child of God.
Every person has to move upward through all these stages to be restored. Even though you may achieve the position of children, or even if Cain and Abel achieve unity, there is no way to go all the way vertically to God if there is no foundation of restored, unfallen parents. Therefore, God has been trying throughout history to establish the True Parents. The True Parents will create for the first time, the way to reach God Himself and for Cain and Abel to be united. In this process of restoration the change of blood lineage has to take place. No one can establish this kind of thing by themselves.
It is only when Cain and Abel are united that the ideal parents can appear. Unless Cain and Abel become one, the ideal parents cannot be restored. Unless the unity between these two is achieved, not only can you not find the path to return to the parents but also you cannot restore the parents. This condition of indemnity can be fulfilled when the spiritual children and the physical children become united in perfect harmony. By this condition, we can restore the unity lost between Adam and the archangel before the fall.
If your spiritual children and your physical children are united into perfect oneness on the horizontal plane, you can be restored to the position of true parents, which is the position of the ideal love of God, for the first time. It is the path of the Unification Church to successfully indemnify horizontally this vertical historical course of restoration.
Therefore, you absolutely need spiritual children. What do spiritual children signify? Adam had three archangels, right? Eve also had three archangels. Adam and Eve could not become the perfected son and daughter of God unless these three archangels start attending them from the moment of their birth and through all of their lives as their servants. Thus, you must restore the people representing the archangels' positions through indemnity.
From this viewpoint, you, men and women alike, need three spiritual children representing three archangels, horizontally. Those three archangels have to unite with you perfectly.
God first created the archangels. Then God created Adam and Eve on the foundation of the complete unity with the archangels. We have to restore that standard ourselves. Before having physical children, spiritual children have to be born. Physical children are to be born only on the foundation of spiritual children, just as God created and united with the angels completely first, and then created Adam and Eve second. That is the Principle.