At the end of the 6th century AD, the bishop Gregory decided to ordain the Temple of Concordia for Christian worship. Therefore, in 597 AD the temple was transformed into a church dedicated to the saints Peter and Paul. This change of use was a stroke of luck for the temple, since it was protected from the sad fate of becoming a quarry of materials to be reused to build new buildings in the surrounding area, which happened to the Temple of Olympian Zeus.
But in order to transform the building into a Christian church, numerous changes had to be made that greatly transformed its appearance. First of all, since all churches face west, while temples face east, the wall of the opisthodomos was demolished to create the nave.
In addition, the open spaces between the columns were closed off, and in the walls of the cella (shrine) six arches per side were opened.
The arches are still visible today, even from the outside. The temple, then a place of Christian worship, ceased to perform its religious functions in 1748, when it was decided to return it to its original form. The spaces between the columns were reopened and the wall of the pronaos rebuilt.
The Christian faith is still very popular in Agrigento, where two important religious events are celebrated: the Feast of Saint Calogero , the most adored saint, and the Feast of Saint Gerland, patron saint of the city.