Metmom, no doubt over the years you have seen photographs of older catholic cathedrals, and recently may have caught a glimpse of the Sistine Chapel.
Displayed on the ceiling are 9 scenes from Genesis, prophets, and other important figures from the Bible. Up until 1450, there were only a handful of hand transcribed bibles. With the arrival of the printing press, the number of books increased but were still quite costly. People learned their faith in church. Moreover, the use of images, stained glass and carvings helped to enhance the transmission of the faith. In the city of Florence, Italy, for example, there stands a large building known as the Baptistery. The proto-Renaissance doors consist of 28 quatrefoil panels, with the twenty top panels depicting scenes from the life of St. John the Baptist. The eight lower panels depict the eight virtues of hope, faith, charity, humility, fortitude, temperance, justice and prudence.
Literacy is the ability to read and write. Up until the turn of the 19th century, literacy was limited to those who could afford to hire private tutors. There are still many parts of the world where illiteracy rates are very high. My great, great grandmother, who arrived in the US from Ireland around 1875, was illiterate. We have several female parishioners from the Middle East who are totally illiterate. They sign checks with an "x". The Catholic Church, which compiled the books that make up the Bible used by christians, used multiple means to convey the story of salvation. You take for granted that everyone is like you. Humility is a good practice.
