Christ is referred to as a lamb in Christian theology because of the symbolism associated with lambs in the Bible. In the Old Testament, lambs were often used as sacrifices in religious rituals, and they were seen as symbols of innocence and purity.
In the New Testament, Jesus is referred to as the "Lamb of God" because he is believed to be the ultimate sacrifice for the sins of humanity, and his death is seen as a substitutionary atonement for human sin. Additionally, the lamb imagery in the Bible also points to Jesus as the fulfillment of the Old Testament sacrifices and prophecies.