Claim. What ties filial child, patriot, saint, and divine child together is not duty but true love; without true love, none of the four ranks is real.
Elaboration. SMM names the binding agent: “The marrow of all this is true love. It is unchanging and absolute true love. However, humankind has been wandering about in ignorance of true love and the fact that it establishes the ties that bind absolute filial children, absolute patriots, absolute saints, absolute divine children and absolute parents” (CSG 14.3 §2, 206-62, 1990.10.3). The reduction is also stated negatively: “The conclusion is that without true love there is no such thing as a filial child” (286-300, 1997.8.13). The argument explains how the four stages avoid being a moral hierarchy of merit — they are mediums of one substance, true love, applied at progressively larger scopes. Take true love away and the curriculum collapses into mere social virtue.
See also. csg-true-love · csg-free-sex-undoes-filial-piety-and-loyalty