Among Poitiers’ remarkable buildings, the Baptistère Saint-Jean stands out: it is the oldest existing Christian building in France, dating in part back to the middle of the 4th Century. Christianity was slow to take hold north of the Alps, and in Gaul first took hold along the valley of the Rhone River, brought there by merchants landing along the ports of the lower Rhone. The first known evangelist of Aquitaine was Martial, in the mid-3rd Century. A century later, after Emperor Constantine’s conversion and declaration of tolerance, Poitiers had its first Bishop, Saint Hilaire, who is thought to have led the construction of the Baptistery around 360 AD.
Christianity in this period received a great many converts, who were for the most part adults. Their baptism, signaling their acceptance of the new religion, was a momentous occasion, as it had been when John the Baptist baptized Jesus. In this period baptism by immersion – the sinking of the convert washed away their sins and prepared them to become “new people,” Christians — was the rule, and could only be celebrated three times a year – at Easter, Pentecost, and Epiphany. This in turn required large spaces – originally outdoors in rivers, or lakes, and over time in covered spaces, which became standalone baptisteries. In the 4th Century when Saint-Jean was first built here, the then cathedral of Poitiers stood closer to it than it does now. The baptismal basin, into which converts would sink their bodies to receive the sacrament, in the center of the building, and the walls of the central room up to the windows, date from Hilaire’s period; archaeologists have found traces of a second adjoining room from the same period, possibly indicating that one baptismal pool was for male converts, and the other for women. In the early 5th Century, in 419 AD, the Wisigoths “purchased” Poitou from the Romans, and had one of their royal residences here at Poitiers. Wisigothic leaders were often Christian (albeit of the Arian version), and Saint-Jean is about the only place one can stand and imagine Wisigoths bathing. After the Franc conquest in the 6th Century, the Baptistery was repaired and expanded, and most of the building dates from this period. As time went by, child baptisms increasingly replaced adult baptisms, and the sacrament was administered by sprinkling rather than immersion: baptismal fonts inside churches became the rule, and by the 9th Century no one built standalone baptisteries any more.
The building also contains several Merovingian-era stone sarcophagi, dating from the 5th to the 7th centuries, assembled from throughout the region, and a number of 11th century frescoes. This landmark of early Christianity in France survived over a millennium and a half, but almost failed to survive the 19th Century. In the urban renewal furor which gripped France under the Second Empire, best-known for Baron Haussman’s demolition of much of old Paris, authorities in Poitiers demolished the old Roman Arena, and planned to dismantle the Baptistery as well. Both Saint Jean and the Abbey of Sainte-Croix, dating back to the 6th Century, were to be removed to make was for the new Boulevard du Pont-Neuf. The Abbey was indeed (mostly) destroyed, but Saint-Jean was saved through the visible expedient that is all visitors’ first impression of the monument: the Boulevard circles around the Baptistery, leaving it on an island. One imagines that even for the forces of urban renewal, early Christianity’s impression sunk in.
