In the Middle Ages, most people were illiterate and could neither read nor write. In order to learn their faith, the churches and cathedrals these people attended were filled with images and artwork which told them the stories of the Bible and used symbols to teach them about their faith. This practice has continued in modern churches, especially in the use of stained glass windows. The twenty-one stained glass windows of St. Peter Church depict stories from the life of Christ.
The windows in the sanctuary depict four of the five Glorious Mysteries of the Rosary. Originally, the fifth mystery, The Descent of the Holy Spirit, was to be on the back wall of the sanctuary. This plan was never completed, but the outline of where the window would have been can be seen on the back of the church.
The windows in the nave of the church depict the life of Christ from the Annunciation to the Crucifixion. Each window contains a depiction of the story it is telling in the main part of the window and then contains symbols related to that story in the square below and triangle above. There are also windows above the confessional and cry room depicting the Sacred Heart of Jesus and the Immaculate Heart of Mary.
St. Peter Receiving the Keys to the Kingdom of Heaven
Located in the choir loft, this large window depicts St. Peter receiving the Keys to the Kingdom of Heaven from Jesus. It is the only window in the church to feature tracery and contains the crossed papal keys and tiara at the top.
The Baptism of the Lord
Located in what was originally the church's baptistery, these windows depict St. John the Baptist baptizing Jesus in the Jordan River.
The Prodigal Son
Located in the transept on St. Mary's side, this window depicts the parable of "The Prodigal Son" at the moment when the prodigal son is welcomed home by his father.
Jesus Teaching in the Temple
Located in the transept on St. Joseph's side, this window depicts Jesus teaching the scribes and elders in the Temple in Jerusalem.
"Suffer the Little Children to Come Unto Me"
Located in the cry room, this pair of windows depict Jesus and Mary welcoming children to listen to the Gospel message.
"The Harvest is Great, But the Laborers Are Few"
This window is located in the stairs leading down to the basement of the church on St. Joseph's side. The windows depict Jesus and St. Joseph, the patron saint of workers. The passage depicted refers not to an actual harvest, but to the mission of spreading the Gospel message.
Located in the stairwell leading to the choir loft, this window depicts St. Cecilia, the patroness of musicians, with an early organ.