The Stained Glass Windows of St. Didacus Church Stained glass windows in the church have always added beauty to the church and added to the sense that there is a sacred place, but they have also had the purpose of being an instrument of instruction and catechesis. Especially in the middle ages when so few people could actually read. The visual symbols and pictures depicted in the windows of a church were an illustrated catechism. With the idea of being both decorative and instructional, the stained glass windows were added in the parish church during the second half of the 1990's.