How do we know Jesus is both God and Savior?

In Mary's song, she identifies the child within her as 'God my Savior.' This acknowledgment points to the essential Christian doctrine that Christ is both fully God and fully man. Theologically, this duality is necessary for our salvation; we need a Savior who is both divine, to merit our salvation, and human, to represent humanity. The historical significance of the incarnation is central to the belief in Jesus Christ as our Redeemer—He is our God manifested in the flesh, capable of offering Himself as an unblemished sacrifice for our sins.