Final answer:
The parts of the imperial ritual in Justinian's church of Hagia Sophia primarily involved the Imperial Door, narthex, nave, and apse. These architectural elements underscored the ceremonial procession of the emperor and the interplay of religious and imperial significances, with mosaics emphasizing the theological narrative alongside imperial imagery.
Step-by-step explanation:
The imperial ritual in Justinian's church of Hagia Sophia involved various parts of the building's architecture, reflecting the ceremonial practices and the theological significance attributed to this grand edifice. One crucial element in this imperial ritual was the Imperial Door, which served as the gateway for the emperor's entrance into the main body of the church. Above the Imperial Door, a mosaic depicting a frontal Christ sitting on a lyre-backed throne, accompanied by an angel and a figure believed to be the Mary, demonstrates the interweaving of religious symbolism with imperial ceremony. The Emperor moved through the narthex, into the nave, the central area for worshippers, and finally towards the apse, the semi-circular area at the eastern end of the church that housed the altar.
Additionally, the Hagia Sophia, with its innovative architectural expression such as the dome supported by pendentives, represents the monumental ambition of Justinian's era and imperial grandeur. The vastness of the nave and the illumination from the clerestory also contributed to the grandeur and reverence of the ceremonies conducted within the church's walls, functioning as a stage for the emperor to manifest his devotion and divine right to rule. As a central point next to the imperial residence, the Hagia Sophia not only served religious purposes but also played an important role in the social and political life of Constantinople during the reign of Justinian I.