Why was the seven-year period for Israel postponed to the future and the church age inserted in between?
The seven-year period was postponed because Israel did not respond to the offer of the King and the kingdom; it was pushed into the future. In between, God calls out the body of Christ during the church age, the age of grace, dealing primarily with Gentiles while Israel is dispersed.
Les explains that this seven-year period was for Israel, but Israel did not respond to the offer of the king and the kingdom, so it was shoved out into the future. In between, God calls out the body of Christ—the church age, the age of grace. He reminds us that God did not deal with the church back when He was dealing with Israel; that was Jew only. Now He is dealing primarily with the Gentile, while the Jew is out in dispersion. Before He can come back and deal with Israel again in the final seven years, the Gentile body of Christ has to be removed from the scene, because God does not deal on both sides of the fence at the same time. As the church age winds down and the final Gentile is brought in, the church is taken out, Israel is back in the land, and ready to be dealt with in the tribulation events.