Familiar biblical stories are clearly an important theme in stained glass. The pictorial narratives, which generally are read from bottom of the window to the top, were structured to emphasize allegories and moral aspects. The stories often contain scenes recorded in non-biblical sources like poems and theological writings. This did not, however, make the stories any less valid or holy.
Common scenes found in nearly every medieval church include the Lord's Supper (images 2 & 3), the creation and mankind's fall (image 1), and the end of the world as told in the Book of Revelations (images 4 & 5). The life and work of saints, such as John the Baptist in image 6, and old testament heroes, such as King David in image 7, were also ubiquitous in stained glass.
Such images might have served to educate some people about the stories, but most importantly, they reinforced the stories people already knew. These images in bright colors brought the stories to life in a time where few had access to illustrated books or other images of the biblical stories. Stained glass, along with sculpture, was the primary mode of physical experience with the church's teachings.