A person’s soul is created immediately by God at the moment of conception. It does not exist before that time. Using NFP for just cause, as the Church allows, is not “frivolous.” God allows human beings to cooperate with him in the creation of new human beings and he takes into account human free will in doing so. If a couple does not have just cause to use NFP and uses it for selfish reasons, the couple may be culpable for their selfishness.
