What were Peter and the apostles preaching in the early chapters of Acts, and how did Israel respond?

Les explains that throughout the early chapters of Acts, Peter and the apostles were promoting Christ as the Messiah of Israel, along with His coming kingship and His Kingdom. They were not at fault; Peter had done all he could and preached his heart out, but Israel rejected the message. Israel could not believe that anything good came out of Nazareth. As Israel kept slipping and slipping away in unbelief, Peter, the eleven, and the Jewish leaders of Jerusalem were losing their clout, and the whole system was falling through the cracks. But God was not out of it: as Israel rejected all this, God turned to the Gentiles, and as the Jews went down, the Gentiles came out. This became Paul's ministry. In verse 6, those who seemed to be somewhat were the twelve and the elders at Jerusalem, but they no longer had the power rightfully as God had entrusted it to them.