If Israel repented of killing their Messiah, would everything still go according to God's plan?
Yes. If Israel repented of what they had done—killing their Messiah—then everything would still come along as God had intended it. Repentance would not derail the divine plan; rather, everything would fully continue according to God's intended purpose.
Les explains that Israel's repentance over having killed their Messiah would not have stopped God's plan; everything would still come along as God had intended it. In the Acts passage, the religious leaders heard Peter and the eleven and were cut to the heart, showing the Spirit was working even on them. Yet religionists hate the truth and have only one way to deal with enemies—kill them—so they sought to slay the apostles. Gamaliel, a Pharisee and doctor of the law, then advised the council to take heed and put the apostles aside for a little space.