Final answer:
The hypostatic union describes the mystical synthesis of Jesus Christ's divine and human natures, established as a doctrine by the early Christian Church and culminating in the Council of Chalcedon in 451, where Jesus is acknowledged both fully divine and fully human in one person.
Step-by-step explanation:
The term "hypostatic union" in Christian theology describes the union of the divine and human natures of Jesus Christ, which is a core doctrine established by the early Church, especially crystallized after the Council of Chalcedon in 451. This doctrine maintains that Jesus Christ is both fully divine and fully human, with these two natures existing in one person without mixing, change, division, or separation. Hence, the unity of the divine and human natures in Christ is not something that can be described as separate and distinct, nor blended into a new nature, nor sequential, but rather it is a mystical synthesis where the two natures coexist uniquely in the Person of Christ.
Mystical experiences in various religious traditions often speak of the unity of the subject with its object, such as the unity of an individual's soul with the divine or with the ultimate reality. The hypostatic union is a specific instance of such mystical unity within Christian doctrine where it is believed that Christ is the perfect bridge between God and humankind because of his dual nature, something anticipated in the miracles and religious sentiments of encountering the supernatural.