photo - St. Peter Cathedral collection
click on Mosaic of Christ the King, The Paschal Lamb, Angels on Left
and Angels on Right for a closer view

he mural on the back wall represents the Lamb of God as depicted in Revelation 5:1-14.  Jesus Christ is the Lamb of God who is the only one able to open the scroll and break the seven seals.  The dove above the lamb represents the Holy Spirit.  Encircling the Paschal Lamb and the Holy Spirit are the Cherubim with angels at the Lower right and left corners.