Luke 24:44 Now He said to them, “These are My words which I spoke to you while I was still with you, that all things which are written about Me in the Law of Moses and the Prophets and the Psalmsmust be fulfilled.”
45Then He opened their minds to understand the Scriptures,
Jesus did not merely allude to the fact that He had fulfilled the scriptures He opened their minds so they could understand it spiritually. When Jesus says the Law, prophets and Psalms He means the whole Book. Because of this I could bring up any Messianic scripture in the OT. They were not the only ones who got this lesson compare this Luke 24:47. Are there OT scriptures that speak of the Messiah atoning for our sin by His suffering? Certainly there are. One prominent example is the entire 53rd chapter of Isaiah. Here are some key verses:
5 But He was pierced through for our transgressions,
He was crushed for our iniquities;
The chastening for our peace fell upon Him,
And by His scourging we are healed.
6All of us like sheep have gone astray,
Each of us has turned to his own way;
But the LORD has caused the iniquity of us all
To fall on Him.
(Isaiah 53:5-6)
And the good pleasure of the Lord will prosper in His hand.
11 As a result of the anguish of His soul,
He will see it and be satisfied;
By His knowledge the Righteous One,
My Servant, will justify the many,
As He will bear their iniquities.
12*Therefore, I will allot Him a portion with the great,
And He will divide the booty with the strong;
Because He poured out Himself to death,
And was numbered with the transgressors;
Yet He Himself bore the sin of many,
And interceded for the transgressors.
(Isaiah 53:11-12)
John the Baptist had said in the beginning that Jesus was the Lamb of God who takes away the sin of the world. What would that mean in the language of a Jew of that time (John 1:29)? He did not say "a" (sacrificial) lamb for Israel but one sufficiently perfect to satisfy the payment capable of saving the nation as the Passover Lamb had delivered Israel in the Exodus, at least all those who had the faith to apply it.
Then there were the scriptures foretelling the establishment of a new covenant with Israel. The Hebrew word for covenant b'rit implies the shedding of blood.
20“A Redeemer will come to Zion,
And to those who turn from transgression in Jacob,” declares the LORD.
21“As for Me, this is My covenant with them,” says the LORD: “My Spirit which is upon you, and My words which I have put in your mouth shall not depart from your mouth, nor from the mouth of your offspring, nor from the mouth of your offspring’s offspring,” says the LORD, “from now and forever.”
(Isaiah 59:20-21)
Jesus rehearsed this event before He went to the cross just as believers have been ever since then.
…27 And when He had taken a cup and given thanks, He gave it to them, saying, "Drink from it, all of you; 28 for this is My blood of the covenant, which is poured out for many for forgiveness of sins.
(Matt 26:27-28)
Finally, turning back to Luke 24, Jesus is quoted as telling them the shedding of is blood was for the forgiveness of sin.
46 and He said to them, “Thus it is written, that the Christ would suffer and rise again from the dead the third day, 47 and that repentance for forgiveness of sins would be proclaimed in His name to all the nations, beginning from Jerusalem. 48“You are witnesses of these things. 49“And behold, I am sending forth the promise of My Father upon you; but you are to stay in the city until you are clothed with power from on high.”
They would be witnesses of Christ's acts, his suffering, His teachings, His resurrection and ascension. They were to proclaim this message beginning at Jerusalem and then move out to all nations. The message of repentance for the forgiveness of sins was only possible because of Christ's shed blood on the cross and His resurrection.