Claim. God is the vertical Parent (the spiritual origin) and the True Parents are the horizontal Parent (the substantial earthly couple at right angles to Him) — human beings were meant to be born at the intersection of both loves.
Elaboration. SMM names the geometry: “It is not God who gives birth to children but the True Parents, and the couple standing in the position of the parents of horizontal true love is the Unification Church’s True Parents. They are the parents with horizontal love standing at a right angle before God, the True Parent with vertical love” (CSG 15.3 §2, 182-258, 1988.10.23). The pair-position is built into creation: “Hence, the love of both sets of parents is necessary. On one hand is the Parent, the Creator, and on the other hand are the physical parents created as the objects of God in pursuit of the ideal.” Reproduction is impossible on the vertical alone: “We might think it wonderful if God could have sons and daughters in the spirit world, but reproduction does not occur there. Why did God create the horizontal parents in the form of Adam and Eve? They were created as the production plant to multiply the citizens of His kingdom” (214-204, 1991.2.2). Vertical and horizontal parents together complete what either alone cannot.
See also. csg-true-parents-are-the-cherished-hope-of-god-and-humanity