What issue did the Third Ecumenical Council address regarding the relationship between Christ's natures?

The Third Ecumenical Council, also known as the Council of Ephesus, primarily dealt with the issue of the unity of Christ's two natures—divine and human. The council was convened in 431 AD and was motivated by the controversy surrounding the teachings of Nestorius, who argued for a separation between the divine and human aspects of Christ to the extent that it compromised the understanding of Christ as a single unified person.

The council affirmed the statement that Christ is one person in two natures, emphasizing that these natures are united without confusion, change, division, or separation. This doctrine was essential for maintaining the Christian belief in the Incarnation—that God became fully human in the person of Jesus Christ while still retaining his divine nature. The affirmation of this unity is pivotal for understanding the relationship between the divine and human in Christ, which is foundational to the Christian faith as articulated in subsequent creeds.

While the other options touch on significant theological issues, they were not the main focus of the Third Ecumenical Council. The question explicitly pertains to the relationship between Christ's natures, which the council sought to clarify and affirm, making the unity of Christ's two natures the central issue addressed.