Was used to convey church doctrine to church-goers and pilgrims, most of whom were illiterate.

church architecture and decoration

Explanation:

Pilgrims were significant sources of funding for monasteries and churches that had the relics of revered saints. Churches were often authoritative buildings that had influential features in the towns and villages where they stood. Books, however, were not crucial to the practice of Christianity, since they only possessed Ancient Greek and Roman texts.

Illuminated manuscripts

This is a manuscript in which the text is supplemented with such decoration as initials, borders and miniature illustrations. Adding decoration made it easier to teach the illiterate given that they could easily infer meaning from illustrations as opposed to text