Why did Satan turn on the nation of Israel after the Abrahamic covenant?
Satan turned on Israel because he understood the Abrahamic covenant was the vehicle God would use to bring the seed of the woman. Therefore he attacked Israel throughout its history, aiming to destroy the nation, since destroying Israel would cause God's whole program to fall apart.
Les teaches that once the Abrahamic covenant was given to Abraham, Satan understood that this was now the vehicle God was going to use to bring about the seed of the woman. So Satan turns on the nation of Israel, and all the way up through Israel's history there is that satanic attack and the apparent desire to destroy the nation of Israel. Les explains that if Satan could destroy Israel, then God's whole program would fall apart. He compares this to the advent of Christianity, where Satan will do everything in his power to disrupt it and destroy it in order to thwart the very program of God.