Chapter 5 contrasts natural parents with True Parents by saying they teach people for different environments. Natural parents train a child for bodily life; True Parents train a person for the eternal world.
The image is vivid: people shaped only for self-centered earthly habits would feel unable to breathe in a realm ordered by living for others. True Parents therefore matter not only as doctrinal figures but as formational ones.
This reframes spiritual life as apprenticeship rather than affiliation. The question is not only what a person believes about heaven, but whether they have been trained to live in its atmosphere.