Allegorical or Predictive? –
Beginning with Isaiah, we have prophecy that describes the rise and fall of earthly empires. All of these empires were future to Isaiah, though to us, they are historical. All of the prophecies of Isaiah except those that concern what is yet in the future, have come to pass, demonstrating that they were intended to be taken literally, not allegorically. It is therefore irrational to suppose that the prophecies that have not yet taken place were intended to be purely allegorical—prophecies about Christ and the Church.