Folks, Peter understood this part of the gospel, and therefore to falsely claim Peter did not understand the gospel at all is false, and unstudied.
The Jews had an excuse for not believing the gospel that Jesus preached to them alone, that is the gospel of the kingdom. You do not have an excuse. You have a complete Bible and testimony of God himself and you have the evidence of history and fulfilled prophecy. You are more guilty than the Jews in your rejection of the kingdom of God.
None of the apostles understood the gospel of Christ at all because it was not preached. Jesus had not died and rose again from the dead. As late as a few days before his crucifixion at Jerusalem as he made made his way from Galilee to be the Passover Lamb, all the gospel writers wrote that they knew nothing about our Lord's death , burial, and resurrection and the report that came from Matthew that Peter resisted it when he first heard of it in Matthew 16, I have already shown. Here is what Mark wrote about it;
Mr 9:9 And as they came down from the mountain, he charged them that they should tell no man what things they had seen, till the Son of man were risen from the dead.
10 And they kept that saying with themselves, questioning one with another what the rising from the dead should mean.
Mr 9:30 And they departed thence, and passed through Galilee; and he would not that any man should know it.
31 For he taught his disciples, and said unto them, The Son of man is delivered into the hands of men, and they shall kill him; and after that he is killed, he shall rise the third day.
32
But they understood not that saying, and were afraid to ask him.
Lu 9:6 And they departed, and went through the towns,
preaching the gospel, and healing every where.
18 And it came to pass, as he was alone praying, his disciples were with him: and he asked them, saying, Whom say the people that I am?
19 They answering said, John the Baptist; but some say, Elias; and others say, that one of the old prophets is risen again.
20 He said unto them, But whom say ye that I am? Peter answering said, The Christ of God.
21 And he straitly charged them, and commanded them to tell no man that thing;
22 Saying, The Son of man must suffer many things, and be rejected of the elders and chief priests and scribes, and be slain, and be raised the third day.
44 Let these sayings sink down into your ears: for the Son of man shall be delivered into the hands of men.
45 But they understood not this saying, and it was hid from them, that they perceived it not: and they feared to ask him of that saying.
Lu 18:31 Then he took unto him the twelve, and said unto them, Behold, we go up to Jerusalem, and all things that are written by the prophets concerning the Son of man shall be accomplished.
32 For he shall be delivered unto the Gentiles, and shall be mocked, and spitefully entreated, and spitted on:
33 And they shall scourge him, and put him to death: and the third day he shall rise again.
34
And they understood none of these things: and this saying was hid from them, neither knew they the things which were spoken.
Joh 20:1 The first day of the week cometh Mary Magdalene early, when it was yet dark, unto the sepulchre, and seeth the stone taken away from the sepulchre.
2 Then she runneth, and cometh to Simon Peter, and to the other disciple, whom Jesus loved, and saith unto them, They have taken away the Lord out of the sepulchre, and we know not where they have laid him.
3 Peter therefore went forth, and that other disciple, and came to the sepulchre.
4 So they ran both together: and the other disciple did outrun Peter, and came first to the sepulchre.
5 And he stooping down, and looking in, saw the linen clothes lying; yet went he not in.
6 Then cometh Simon Peter following him, and went into the sepulchre, and seeth the linen clothes lie,
7 And the napkin, that was about his head, not lying with the linen clothes, but wrapped together in a place by itself.
8 Then went in also that other disciple, which came first to the sepulchre, and he saw, and believed.
9 For as yet they knew not the scripture, that he must rise again from the dead.
10 Then the disciples went away again unto their own home.
I have quoted 10 verses from John. Nine of the 10 is historical and he tells what happened. But one verse is his commentary on why it happened as it did. That is verse 9. I underlined it so you cannot miss it.
The gospel (good news, glad tidings) that Jesus and his disciple preached to Israel was not the gospel of Christ crucified and risen from the dead so men can be saved, it was the gospel of the kingdom of God on the earth. They must believe Jesus is the Son of God before they can believe that his death and burial and resurrection can save them. They must believe he is God in the flesh, without sin. His coming to Israel and his mighty deeds proved to them that he was the one the prophets wrote about . He is the fulfillment of the covenant promises that God swore to Israel in the unconditional covenants , the Abrahamic, the Palestinian, and the Davidic covenants. The new Covenant made with these same people after his death and resurrection assured that his blood would take away all their sins and by extension, the sins of the whole world as God made the heathen to be partakers with Israel in the spiritual blessings of the New Covenant, which is forgiveness of sins in Christ and the gift of the Holy Ghost, his righteousness, in us so we might be one with Jesus Christ in this age.
The only way to receive light from God is to believe his words because the Spirit teaches the saved through the words God has chosen. Do not re-write the testimony of the eye witnesses who wrote what they saw and heard and experienced..