Final answer:
The interior design of Il Gesù is meant to create a setting conducive to preaching and the celebration of the Eucharist, emphasizing the auditory experience and the magnificence of the Baroque period architecture.
Step-by-step explanation:
The purpose of the interior design of Il Gesù is primarily to serve as a grand auditorium for preaching, enhancing the religious and spiritual experience of the congregants. The church's interior was designed with a focus on the auditory experience during sermons and the celebration of the Eucharist, which is a Christian rite considered to be a sacrament in most churches and an ordinance in others. By creating an interior space with a central nave and aisles, the architecture of Il Gesù was carefully planned to direct attention towards the altar and the grand ceiling frescoes, epitomized by the 'Triumph of the Name of Jesus' by il Baciccio, thus making it a theatrical stage for the sacred liturgy. This design not only supported the religious functions of the church but also reflected the artistry and magnificence of the Baroque period, aiming to invoke a sense of the divine.