In 1Peter 2:8 we are told that the Jews who are in unbelief were “appointed” to stumble at Christ (1Peter 2:8)! But, what does this mean? Were the Jews appointed or destined to reject Jesus? I don’t believe this view was Peter’s intent. Otherwise, one might expect him to express some sort of lamentation over the condition of his people, the Jewish nation. Paul grieved over the Jews, wishing he could be accursed from Christ, if that meant his kinsmen (the Jews) were accepted. In other words, he was willing to trade places with his nation, if God would will it so. Yet, nothing like this is expressed by Peter, so how could he mean to say that God intended that the Jewish nation would reject Jesus, their Messiah—the Elect or Chosen One?
The Scriptures says:
and “A stone of stumbling, and a rock of offense.” They stumble because they disobey the word, as they were destined to do. (1 Peter 2:8)
The question is: does the participle “as they were destined to do” modify the clause “…because they disobey the word,” or does it modify the main thought: “They stumble…”? The first interpretation would mean: the Jews were destined to disobey or disbelieve the Word (Logos – Jesus), therefore, they stumbled. The second rendering would mean: the Jews stumbled as they were destined to do, because they didn’t obey or believe the Word (Logos – Jesus). According to the first rendering the Jews didn’t have a choice, and it could be argued that God unjustly punished them. However, in the second rendering God punished them, because of the choice they made. The correct Greek syntax follows the second rendering: God punished the Jews because of the choice they made, regarding Jesus (the Gospel).
To this Paul agrees where in Romans 11:32a he tells us that God has concluded that the Jews as a whole are in unbelief. This was done in order that the promises might be given to those who trust Jesus (Galatians 3:22), and that God might justifiably have mercy upon the gentiles. Jesus tells us that nothing is impossible for God (Matthew 19:25; cf. Luke 1:37). Therefore, it would not have been a difficult matter for God to help unbelieving Jews to understand their error and place their trust in Jesus. Nevertheless, God didn’t choose to do this. Rather, when the Jews expressed their disbelief, God appointed or placed (G5087) them in unbelief. That is, he permitted their decision to disobey or distrust the Logos to stand without his help that would guarantee their change of heart. He didn’t try to change their minds, so that he might offer salvation to the gentiles by reason of the Jews’ unbelief (Romans 11:30, 32).
This idea is also pictured in Jesus’ parable of the householder who made a supper in Luke 14:16-24. When the invited guests asked to be excused (they rejected the supper), the householder sent servants into the streets and highways to invite anyone and everyone else, saying those who had been invited wouldn’t taste of his supper.
Therefore, if God held back his mercy to help unbelieving Jews change their minds, in order that he might have mercy on the gentiles (Romans 11:32), then the integrity of God demands that he eventually show mercy to unbelieving Jews. After all, if God was merciful to the gentiles who had for so long rejected him (Romans 11:30a), then he could justifiably offer mercy to unbelieving Jews who had for so long a time embraced him (cf. Romans 11:28).
 See Charles Bigg, A Critical and Exegetical Commentary on the Epistles of St. Peter and St. Jude, page 133 – reference cited by . Dr. Thomas L. Constable: Notes on 1 Peter (2015 Edition) page 28.