While Agnus Dei refers to Christ, it actually means "lamb of" this
The Lamb of God title is widely used in Christian prayers, and the 
Agnus Dei is used as a standard part of the .... with Romans 3:21-25 for 
atonement, while another view draws parallels with the Paschal Lamb in Exodus 
12:1-4,... [DOC] [TLE] Why is Jesus called the "Lamb of God?"