Ex 12:3, Ex 29:38-39, Acts 8:31-35, Isa 53:5-11, Rev 5:6-7,12,
In the Old Testament, God told us to put the blood of a lamb on the doorposts and eat the meat on the Passover. This is God's foreshadowing of what Christ will shed for us in the future. (Ex 12:3)
Ex 12:3 Speak ye unto all the congregation of Israel, saying, In the tenth day of this month they shall take to them every man a lamb, according to the house of their fathers, a lamb for an house:
In the Old Testament, a lamb was offered as a sacrifice to God for the forgiveness of sins. This is God's showing that Christ will be sacrificed for us in the future. (Ex 29:38-39)
Ex 29:38 Now this is that which thou shalt offer upon the altar; two lambs of the first year day by day continually. 39 The one lamb thou shalt offer in the morning; and the other lamb thou shalt offer at even:
Also in the Old Testament it was foretold that Christ would be led away like a Lamb to die for our sins. (Isa 53:5-11)
Isa 53:5 But he was wounded for our transgressions, he was bruised for our iniquities: the chastisement of our peace was upon him; and with his stripes we are healed. 6 All we like sheep have gone astray; we have turned every one to his own way; and the Lord hath laid on him the iniquity of us all. 7 He was oppressed, and he was afflicted, yet he opened not his mouth: he is brought as a lamb to the slaughter, and as a sheep before her shearers is dumb, so he openeth not his mouth. 8 He was taken from prison and from judgment: and who shall declare his generation? for he was cut off out of the land of the living: for the transgression of my people was he stricken. 9 And he made his grave with the wicked, and with the rich in his death; because he had done no violence, neither was any deceit in his mouth. 10 Yet it pleased the Lord to bruise him; he hath put him to grief: when thou shalt make his soul an offering for sin, he shall see his seed, he shall prolong his days, and the pleasure of the Lord shall prosper in his hand. 11 He shall see of the travail of his soul, and shall be satisfied: by his knowledge shall my righteous servant justify many; for he shall bear their iniquities.
Christ came to this earth. John knew that Jesus was the Christ. That is why John called Jesus the Lamb of God who takes away the sin of the world. (Jn 1:29)
Jn 1:29 The next day John seeth Jesus coming unto him, and saith, Behold the Lamb of God, which taketh away the sin of the world.
Philip explained that Jesus was the Christ to a man who had read Isaiah but did not understand (Acts 8:31-35)
Acts 8:31 And he said, How can I, except some man should guide me? And he desired Philip that he would come up and sit with him. 32 The place of the scripture which he read was this, He was led as a sheep to the slaughter; and like a lamb dumb before his shearer, so opened he not his mouth: 33 In his humiliation his judgment was taken away: and who shall declare his generation? for his life is taken from the earth. 34 And the eunuch answered Philip, and said, I pray thee, of whom speaketh the prophet this? of himself, or of some other man? 35 Then Philip opened his mouth, and began at the same scripture, and preached unto him Jesus.
Jesus is the Christ, the Lamb of God who died for our sins. (Rev 5:6-7,12)
Rev 5:6 And I beheld, and, lo, in the midst of the throne and of the four beasts, and in the midst of the elders, stood a Lamb as it had been slain, having seven horns and seven eyes, which are the seven Spirits of God sent forth into all the earth. 7 And he came and took the book out of the right hand of him that sat upon the throne. 12 Saying with a loud voice, Worthy is the Lamb that was slain to receive power, and riches, and wisdom, and strength, and honour, and glory, and blessing.