What is Amillennialism and how did Augustine start it?

Les explains that Amillennialism grew out of removing the Jew from the prophetic scene: once Israel was treated as no longer viable, end-time prophecy was dismissed. Then, after Constantine opened the Roman Empire to Christianity, Augustine, a Roman Catholic bishop, embraced the idea that Christianity was now usurping the planet and that this was how the Kingdom would come. On that view, the Church is the literal Kingdom, so there is no further need for the Tribulation or the Second Coming. Augustine even held that Satan was defeated and locked up at the Crucifixion and Resurrection, meaning they were already in the Kingdom. Les notes that not long afterward the world slid deeper into sin, showing that view was not true. Augustine thus precipitated Amillennialism: all promises given to Israel were transferred to the Church, and no prophecy remained to be fulfilled. Les also points out that the Reformers—Martin Luther, Calvin, and others—were so focused on salvation, faith, and correcting Roman Catholic excesses that they never seriously considered eschatology or end-time events.