The purpose of this study was to explore the philosophical concepts of marriage in the teachings of Immanuel Kant and Pope John Paul II. The study was based on a hermeneutical approach. The study employed the comparative method to compare the concepts of commercium sexuale (sexual union) and communio personarum (communion of persons); the historical method – to reconstruct these concepts and the preconditions for their emergence; the systemic method – to break down the concepts into separate provisions and analyse them without losing a holistic vision; and the structural method – to search for the hidden structural elements of these concepts and their preconditions. It was found that Kant insists on defining marriage as commercium sexuale – a union based on sexual characteristics. He considers this union to be primarily legal – it is a mutual right granted by both newlyweds to use each other’s bodies and the right to have a permanent impact on each other’s lives. For John Paul II, marriage is not a commercial arrangement, but rather a commitment of the newlyweds to give each other their personalities as a gift. Corporeality and its sexuality, as an integral part of the personality, is also part of this gift. The choice of a partner for marriage is the choice of a person to whom you are ready to promise to give yourself unlimitedly. This study covered the fundamental differences between the theological view of the nature of marriage and the philosophical concept of Kant (which substantially influenced the worldview of modern society and, as a result, postmodernity). The study also found points of intersection between the views of Kant and John Paul II.