When does God stop dealing with the nation of Israel in Acts?

Les explains that Acts 9 is the fork in the road. Israel had reached the high point of unbelief and rejection by saying they would not have Jesus of Nazareth to rule over them, treating Him as an imposter who could never be the Messiah, and Saul was egging them on. At that point God finally left off dealing with the nation of Israel and began something totally different, something never imagined by Peter or the eleven. God in His grace now acts out of the secret recesses of His own mind. The chapter opens with Saul still breathing threats and slaughter against the disciples—meaning followers or believers, not the twelve—going to the high priest for letters to the synagogues so he could bind and bring to Jerusalem anyone who had followed Jesus of Nazareth, men or women. Outside Damascus the Lord struck him down with a beam from heaven, and he heard the voice saying, "Saul, Saul, why persecutest thou me?"