In the part of the prologue that concerns the Church, Beatus follows mainly St Isidore and, to a lesser extent, St Gregory the Great, Tyconius and St Jerome. He provides a short treatise about ecclesiology designed to explain the meaning of Christ, the angels, patriarchs, prophets, apostles, martyrs, clergy, monks, religious and the faithful.

This image, found in branch IIb alone, may perhaps have been an innovation by Maius included in one of the miniatures that has disappeared from the Tábara Beatus: it is exclusive to the extant, tenth-century Beatus and is only to be found again in the later Beatus, albeit in a different configuration having discarded the frieze layout . The provenance of the portrait of the apostles may be two-fold. On the one hand, the collections of biographies on papyrus scrolls were illustrated in Antiquity by portraits: a very widespread procedure. The representation of a figure or author of a text standing or in a medallion has ancient models. When Christians began to add portraits to different books of the Bible, they adapted the standing figure of the author used in Antiquity – the style most commonplace when the scroll was still in use – employing it frequently. As a result, the prophets appear in this pose in particular, sometimes holding the rolled-up scroll in their left hand – as in the famous statue of Democritus – or reading the unrolled scroll, as in the portrait of Euripides or Virgil. After the codex was invented, a trend developed of devoting entire pages to single miniatures and separating them from the text in the columns they were inserted into.