Isa 56 & Matt 16:13-28's Sudden Shocking About-turn from graciousness to being rudely harsh Vs Exo 34:6, Ps 145:8, Ps 103:8 's "Slow to anger" [closed]

The sudden change of tone in Jesus' statements to Peter are neither rude nor hard to understand. Peter had just been given divine revelation from the Father regarding exactly who Jesus Christ is, and made a confession of faith in Jesus. This wasn't his own idea. Jesus clearly said the Father had revealed this massive truth to Peter. This truth needs to be revealed to every person who is to grasp that Jesus is the Christ, the Son of the living God. Without understanding and confessing that monumental truth, nobody can be saved.

Shortly after that, Peter then heard Jesus speak of his impending death, and began to rebuke Jesus. What? He began to rebuke the one who he had just confessed as being the Son of the living God? Peter was an impetuous sort of man, yes, but this was disgraceful! Had he instantly forgotten what Jesus had told him about the Father's revelation? Apparently. Instead of building on the divine revelation of the Father, he blurted out his own ideas. Therefore Jesus did not tolerate Peter's rebuke for one second. Peter's words might just as well come from the devil - it was as if the devil was whispering through Peter, trying to put Jesus off from the sacrificial death that was the reason why he came as man - to die. Therefore Jedus rebuked Peter in the strongest possible terms, and rightly so.

As for the Isaiah passages... Two categories of people are being addressed. At the start of the chapter, the Lord is encouraging those who would observe his ways and refrain from evil. But from verse 9 the tone changes because a different category of person is being addressed. Those in Israel who should have been alert watchmen looking out for the interests of the nation and God's holy name have failed in their duty. They have proven themselves to be greedy, selfish wine-bibbers. There was no chapter break in Isaiah's scroll. The anger of the Lord continues to be expressed from the start of chapter 57. Read through the whole of chapter 57 and see how wicked men are exposed by the Lord as such, while the conclusion is that God dwells with humble and contrite people, granting peace and healing to them. But for the wicked, there is no peace.

Why should anyone be surprised at the Lord's gentle, loving encouragements for those seeking to honour him, and the Lord's sternest rebukes for those who continue to dishonour him?

God always allows enough time for sinners to repent and stop doing evil. But he knows when they are set in their ways, and so hardened in heart, that there is no healing for them. God's wrath will come, eventually. But fools think that because he is long-suffering and patient, they will be able to carry on in their wicked ways and nothing will happen. For such ones, the Bible contains the strongest possible exposure.

"Do not be deceived. God is not mocked. For whatsoever a man soweth, that he shall also reap." Galatians 6:7. And none of them will be able to say God neither warned them, nor gave them enough time to repent. The Bible is full of such warnings, plus real-life examples of the two outcomes for those two types of people.

Regarding the sudden change in tone in Isaiah 56, vs. 9 represents a new section of the poem, or possibly a different poem altogether, which was not originally joined to the first. The following is from a footnote in the NABRE:

56:1–8 This poem inaugurates the final section of the Book of Isaiah... In this opening poem, the references to “keeping the sabbath” (vv. 2, 4, 6), “holding fast to the covenant” (vv. 4, 6) and “God’s holy mountain” as a house of prayer (v. 7), all tell of the postexilic community that was establishing itself again in the land according to the pattern of God’s word given through the prophet.

Isaiah 56:9 represents a switch in focus, predicting what will happen if God's people do not follow the guidelines mentioned in 56:1-8; or it could be a new writing inserted when the Book of Isaiah reached its final form. The NABRE views 56:9–57:21 as a separate section of the Book, but emphasizes that, like the opening section, it offers hope as well as judgment:

This section is made up of two pronouncements of judgment (56:9–57:2; 57:3–13) and an oracle of salvation (57:14–21), each of which ends with a reversal of imagery and language. While there are harsh indictments against the corrupt leaders of Israel (56:9–12), a promise of peace is offered to those who are just (57:1–2).

With regard to Matthew 16, the reason for the abrupt change in Jesus' emotion is that Peter, immediately after being declared the head of the Church, has opposed Jesus' destiny to go to the Cross. Peter's opposition is understandable since in Matthew's narrative (unlike John's where the Jesus' sacrifice is the plan from the beginning), the idea of Jesus' impending death takes Peter by surprise. However, Jesus has just declared that Peter is a rock and will be the head of his Church (vs. 18). To show public disagreement with Jesus was bad enough, but to stand in opposition to "Christ crucified" could not be tolerated. Thus, Matthew and Mark both present Jesus as harshly scolding Peter for this.

Conclusion: Sudden changes in the divine attitude as expressed in the Bible are due to a variety of causes. In Isaiah 56, the change marks a shift from section to another, possibly representing two distinct writings that were not originally joined. In Matthew 16, the shift is used by the author to emphasize the seriousness of denying that the Cross was essential to God's plan of salvation.