Book 15 resists the idea of heaven as mainly an individual destination. It describes heaven as the dwelling place of true families and treats solitary salvation as incomplete.
That reframes discipleship. The question is not only whether a person is inwardly sincere, but whether love has become ordered enough to sustain family-shaped belonging.
This is useful pastorally because it challenges modern spiritual individualism without collapsing into mere traditionalism. Heaven is communal because love is communal.