Why does Les view Acts as the fall of Israel?
Acts records Israel's final rejection of their Messiah and refusal to have Him as king. Because of that rejection, God disperses the nation, takes away the temple, and turns to the Gentiles—though some Jews are still saved. Israel falls away while Gentiles and the Church come up, so Acts primarily documents Israel's fall.
Les explains that the first seven or eight years of Acts still show God dealing with Israel. Then God raises up the apostle Paul, and He begins that Gentile dealing with the house of Cornelius, even at Peter's preaching. It had to be that way so Peter could come to Paul's defense. Then Israel falls away, the Gentiles are coming up, the Church is coming up—and that's the book of Acts. Les notes that most have always been taught Acts was the account of the birth of the Church. It is, but primarily he prefers to look at Acts as the fall of the nation of Israel. In Acts, Israel finally rejects their Messiah completely; they will not have Him to be their king. So God puts them into dispersion, takes away their temple, and turns to the Gentile—not exclusively, because some Jews are still being saved. But for the most part, the last 1900 and some years have been God calling out Gentiles, comprising the Body of Christ. Acts was written by the same gentleman who wrote the Gospel of Luke.