The Council of Chalcedon was an important church assembly held in 451 AD in the city of Chalcedon, near modern-day Istanbul. It aimed to address the nature of Christ and resolve disputes arising from differing theological views. The council affirmed the doctrine of the two natures of Christ, stating that He is both fully divine and fully human, a belief that became central to mainstream Christianity. The council produced the Chalcedonian Definition, which clarified the relationship between Christ's divine and human natures. This definition was significant in shaping Christian orthodoxy and led to further divisions, particularly with groups like the Monophysites, who rejected the dual nature doctrine.