The beginning of the gospel of Jesus Christ, the Son of God. As it is written in Isaiah the Prophet: “Behold, I send My messenger before Your face, Who will prepare Your way before You. The voice of one crying in the wilderness: ‘Prepare the way of the LORD; make His paths straight.’” (Mark 1:1-3)
Some think that Old Testament prophecies set into motion a chain of events that are finally fulfilled in an event of the New Testament or in the life of Christ. However, many Patristic writers tried to disabuse believers of that thinking. For these Church Fathers, prophecy doesn’t set into motion the event they are predicting, nor does it predetermine the event. Rather, the prophets are given a glimpse of something that has not yet occurred, and they write about what they saw as if it had occurred already, even if they write sometimes in shadow or figuratively. So, they are not determining the outcome of an event by their prophecy, but rather are reporting on something revealed to them. [That prophecy doesn’t predetermine what will happen is clear in the biblical Book of Jonah – Jonah prophesies the disaster that will strike Nineveh (and Jonah is hoping and wishing the disaster is going to happen as he sees the Ninevites as his enemies). However, the Ninevites repent, and God does not devastate their city (to Jonah’s disapproval). Jonah the prophet foresaw the disaster, but it never happened! God changed the course of events when the Ninevites changed their lives (repented).]
So, Origen, in the 3rd Century teaches:
We say that the one who made the prediction was not the cause of the future event, because he foretold that it would happen; but we hold that the future event, which would have taken place even if it had not been prophesied, constitutes the cause of its prediction by the one with foreknowledge. (Origen, Cels 2.20)
As Orthodox scholar John Behr comments:
It is because Christ died on the cross that the prophets spoke about this, not because they spoke about it that he had then died, and, in fact, when they spoke about it, they did so, as we noted earlier, as a past event, and, given that it’s happening is the ’cause’ of the prophecy, Christ himself speaks of it as an eternal necessity (cf Luke 24: 26). (ON FIRST PRINCIPLES, p lxxxi)
The event is the cause of the prophecy; the prophecy is not the cause of the event. It is not because the prophets said it, that an event occurs “to fulfill” the prophecy. Rather, the event when it occurs is what the prophets were allowed to glimpse, this is what fulfills a prophecy and determines that the prophecy was real – the event actually happens. The prophets don’t say something and then God has to scramble to arrange the event. God allows the prophet to see something that God will do and the prophet merely speaks to what he/she has seen, whether or not he/she can understand the prophecy. The prophets thus are really forth-telling as to what God is doing rather than foretelling.
And if you say in your heart, ‘How may we know the word which the LORD has not spoken?’ — when a prophet speaks in the name of the LORD, if the word does not come to pass or come true, that is a word which the LORD has not spoken; the prophet has spoken it presumptuously, you need not be afraid of him. (Deuteronomy 18:21-22)