Chapter 8 is devoted to the ways in which some Nicene bishops attempted to persuade kings to convert, illustrated by the examples of Avitus of Vienne and Leander of Seville, and to conversion as a political project and as a theme of the ideology and theology of kingship in late sixth-century Visigothic Hispania. Conversion and royal rule in Gaul and Hispania were also linked to another important phenomenon: the cult of saints. Thus, in this chapter three cults that played an important role in Nicene–Homoian relations are analysed: the cults of the apostle Peter in Burgundy, of Martin of Tours in Gaul, and of Eulalia of Mérida in Visigothic Hispania.

The “Holy Heads” of Peter and Paul, attested in the 11th century within a secondary altar of the Laurentius-Oratory in the Patriarchium Lateranense and later on inside the main altar of the Sancta Sanctorum, increased their status exponentially after having been transferred by Pope Urban V (1368-70) into the Lateran Basilica. Embedded in two huge, lavishly decorated anthropomorphic reliquaries they were enclosed high up in the new tabernacle above the main altar of the Cathedral of Rome. The new mise-en-scène emphasized their role as symbols of the double apostolicity of Rome and of the Roman Church restored after the return of the Papacy from Avignon. In the late 14th and15th Century the Capita apostolorum became one of the most prestigious relics in Rome in competition with the Veronica at the Vatican. The skulls of Peter and Paul in their precious containers – displayed only few times a year – attracted not only pilgrims, but also thieves. A lost fresco cycle in the transept painted shortly after the attempt to steal some jewels and gems from their reliquaries at Easter 1438 should have deterred potential thieves with its representation of the cruel punishments inflicted on the alleged culprits.