There are various kinds of millenialism. It’s quite true that dispensational premillenialism is a modern notion. But straightforward premillenialism (Christ will return and set up a kingdom that will last a thousand years before the final End) does appear to have been the dominant opinion of the Church in the second century. At least, all the Fathers of that era of whom I’m aware taught it–and I’ve read most of them. This isn’t a huge body of material, and a lot has been lost. So it’s possible that there were non-millenialists who haven’t come down to us. But such arguments from silence are very dubious. The downfall of millenialism appears to have been Constantine–once the Church was tolerated, most Christians concluded that the reign of Christ was being fulfilled in their own day.
Postmillenialism, which is what I’d argue the Catechism condemns under the term “millenialism,” was common in the Middle Ages, and held by some radical groups in the Reformation era. It was also the belief of many of the Puritans and of most 19th-century Protestants before the rise of dispensationalism.
A good book on medieval radical millenialism is Norman Cohn’s The Pursuit of the Millenium.
In Christ,
Edwin
