There was a man sent from God, whose name was John. He came as a witness to testify to the light, so that all might believe through him. He himself was not the light, but he came to testify to the light. (John 1:6-8)One of the fascinating aspects of Christian theology -- one which is often misunderstood in contemporary discourse on religion -- is the doctrine that God makes use of secondary causes to accomplish his purposes. God is not merely one more thing in the universe like you and me, in competition with every other being for some space in causal arena. Rather, God is beyond this universe entirely, and does not operate on the same level at all. It is not as if either God prepares the way or else John does; rather, God can prepare the way for the advent of Christ into the world through John the Baptist.
God makes use of means, in other words, to accomplish the things he want. This is significant because we often assume that an event or phenomenon either was caused by God, or else it is entirely a result of natural causation. For that reason, so many people these days say something like the following: you shouldn't thank God for the food on your table; you should thank the farmers who worked to produce it. This is a false dichotomy, because it isn't as if either the farmers or God made the food, but not both. Rather, all things whatsoever come from God, and all things happen naturally and in an orderly manner (e.g., the rains, the growth of crops, etc.) thanks to God's preserving the world and its laws in existence.
In the same way, God makes use of John to prepare the way for the advent of Christ. He doesn't simply arrive on the scene at random, but rather sends John to alert people to the imminent arrival of Christ. Why should he do this? It must be because people needed to be reminded, yet again, of the coming of the messiah. Once more, the terrain had to be prepared, so that the Christ could come and people could be brought to the place in which they were to make a choice -- whether to believe in him or not. People needed to know that Christ was coming, so that they could make an informed choice whether or not to accept him.
In an interesting way, John the Baptist's arrival in Judea is an allegory for the activity of the Holy Spirit, preparing a place for Christ in the heart of the person who would become a Christian.
I considered in an earlier post that people, because of their sinfulness, did not recognize the Logos who created them when he came into the world. Because of the deeply ingrained sinful ways of thinking and acting in them, they were not capable of seeing the truth when it was presented to them. Yet every man, at the same time, is called to believe in the gospel. And nobody can believe in anything unless he recognizes at least a glimmer of the truth in that which is brought to his consideration. So man is simultaneously required and incapable of to recognize at least the glimmer of the truth in the gospel and to believe. How can this problem be resolved?
The answer, of course, is that the Holy Spirit enables a person to believe in the gospel. Through a mysterious saving activity, such that only God in principle could do such a thing, the Holy Spirit convicts the world, as Jesus says later on in the Gospel, so that they might believe. And in this way, too, John the Baptist comes as an external representation of that interior work of the Holy Spirit. John comes and preaches repentance to the Judeans, so that all might believe through him. And in the same way, by various mysterious means, so also the Holy Spirit reaches out to all people through their circumstances, through other people, and through whatever other medium he might choose, so that they might believe and be saved.