Final answer:
Santa Sabina's primary function in late antique Europe was to act as a congregational space for Christian worship, reflecting the legal and official status of Christianity post-Constantine. It held differentiated areas for different groups of worshippers, within a traditional Roman basilica layout, adapted for Christian liturgical needs.
Step-by-step explanation:
The primary function of the Interior of Santa Sabina in Rome around 450 C.E. was as a congregational space that demonstrated the legality and official status of Christianity, after it was declared a state religion in the Roman Empire.
This early Christian basilica would have included specific areas for different congregants: a nave for the general congregation, side aisles which historically may have been used by women, and an apse where the clergy would be situated during services. Its structure represents a transformation from the multipurpose Roman basilica, suited for secular activities, to a space constructed to serve the Christian liturgical functions and to accommodate the Christian population's religious practices within a large, interior space that signified the growing influence and authority of Christianity.
While some structures like Old St. Peter's Basilica developed into a cruciform shape, Santa Sabina retained the traditional basilica form without side aisles, indicative of the evolution of church design to meet the spiritual and functional needs of the Christian community within the Roman architectural heritage.