The motto "Deum Adora" (Worship God) is taken from the Book of Revelation 22:9. When St. John seeks to worship the angel who has shown him the great visions of the book, the angel rebukes him: "Worship God." It is God who claims our adoration and loyalty, in worship and in action. St. Thomas More expressed this when in his last words before martyrdom he said: "I die the king’s good servant, but God’s first." Our priorities in life must be clear and determined by our adoration of the Lord. The shield with a gold cross on a red background is based on that of St. Peter's Seminary. The Alpha and Omega recall the Book of Revelation 22:13, where Jesus says: "I am the Alpha and the Omega, the first and the last, the beginning and the end." The open Bible and the chalice represent the two great ways in which we experience Jesus in the Church, in Word and Sacrament.
The above taken from the Archdiocese's webpage. Click title to link.