What is the significance of the body & blood of Jesus ?

Jesus talks about his spiritual body & blood to be shared among his disciples and followers for their forgiveness and eternal salvation, that we may be transformed into the likeness of Christ. 

John 6:32 “Then Jesus said unto them, Verily, verily, I say unto you, Moses gave you not that bread from heaven; but my Father giveth you the true bread from heaven. For the bread of God is he which cometh down from heaven, and giveth life unto the world. Then said they unto him, Lord, evermore give us this bread. And Jesus said unto them, I am the bread of life: he that cometh to me shall never hunger; and he that believeth on me shall never thirst.”

Matthew 26:26 While they were eating, Jesus took bread, and when he had given thanks, he broke it and gave it to his disciples, saying, “Take and eat; this is my body.” 27 Then he took a cup, and when he had given thanks, he gave it to them, saying, “Drink from it, all of you. 28 This is my blood of the[b] covenant,which is poured out for many for the forgiveness of sins.

Reference from Torah

Leviticus 17:11 “For the life of the flesh is in the blood: and I have given it to you upon the altar to make an atonement for your souls: for it is the blood that maketh an atonement for the soul.”

Hebrews 9:19 For when every commandment had been told to all the people by Moses in accordance with the law, he took the blood of calves and goats,[p] with water and scarlet wool and hyssop, and sprinkled both the scroll itself and all the people,20 saying, “This is the blood of the covenant that God has ordained for you.” 21 And in the same way he sprinkled with the blood both the tent[q]and all the vessels used in worship. 22 Indeed, under the law almost everything is purified with blood, and without the shedding of blood there is no forgiveness of sins.

Hebrews 9:28 so Christ, having been offered once to bear the sins of many, will appear a second time, not to deal with sin but to save those who are eagerly waiting for him.

Answering Islam

فَإِن كُنتَ فِي شَكّٖ مِّمَّآ أَنزَلۡنَآ إِلَيۡكَ فَسۡـَٔلِ ٱلَّذِينَ يَقۡرَءُونَ ٱلۡكِتَٰبَ مِن قَبۡلِكَۚ لَقَدۡ جَآءَكَ ٱلۡحَقُّ مِن رَّبِّكَ فَلَا تَكُونَنَّ مِنَ ٱلۡمُمۡتَرِينَ

Surah 10:94 If you ˹O Prophet˺ are in doubt about ˹these stories˺ that We have revealed to you, then ask those who read the Scripture before you. The truth has certainly come to you from your Lord, so do not be one of those who doubt