Imagine this scene: Jesus is with his disciples at the Last Supper, and he begins to teach them:
“I am God the Son, God from God, Light from Light, true God from true God. I am eternally begotten and of one substance with the Father. God is actually three persons – Father, Son and Holy Spirit – but only one divine nature. I am one divine person, but I have both a human nature and a divine nature.”
At this point I can just see Peter scratching his head, looking over at John, and going “huh?”
Of course, Jesus didn’t say the above, even though all of it is true, and is actually the bedrock of Christian belief about the Godhead and Jesus Christ. In today’s Gospel reading, Jesus states quite plainly why he didn’t give such a speech: “I have much more to tell you, but you cannot bear it now”, but then he follows this disappointing statement with a promise: “But when he comes, the Spirit of truth, he will guide you to all truth.” (John 16:12-13).
This is the foundation for the concept of development of doctrine. The mysteries of God are infinite, but the human mind is quite finite. Thus God simply cannot reveal all truth about Himself and His work immediately, but instead must do so incrementally. We see this clearly in the Old Testament, as God slowly leads His children to a deeper understanding of His nature as a loving and merciful God, and also prepares them for the coming of His Son. After the Revelation of Jesus Christ, there is no need for further revelation, but there is a need for a deeper understanding of that revelation. And that quest for deeper understanding can be a long, drawn-out process. As Jaroslav Pelikan, author of The Christian Tradition, a five-volume work on the development of Christian doctrine, once said,
For those who believe that you don’t need tradition because you have the Bible, the Christian Tradition has sought to say, “You are not entitled to the beliefs you cherish about such things as the Holy Trinity without a sense of what you owe to those who worked this out for you.” To circumvent Saint Athanasius on the assumption that if you put me alone in a room with the New Testament, I will come up with the doctrine of the Trinity, is naive. So for these readers I have tried to provide a degree of historical sophistication, which is, I believe, compatible with an affirmation of the central doctrines of Christian faith.
An understanding of the Christian mysteries entails hard work, especially for those who first received them. We do not live in a Matrix-style world, in which God simply dumps information into our minds; instead we are made to learn by meditating over information over a period of time. And in the case of the doctrine of the Trinity, it took over 300 years – with the guidance of the Spirit of Truth – to finally come to even a basic understanding of that mystery that could be put into human language.
The greatest expositor of the concept of the development of doctrine is of course John Henry Cardinal Newman. It was in fact his recognition of the development of doctrine that led him into the Catholic Church. He studied the early Church and realized that it was the earlier form of the modern Catholic Church – not identical, but instead a younger version of itself. Just like in his middle age he was not identical to his youthful self, so too the Church grows and develops over time.
But this growth is not haphazard and completely dependent upon sinful, finite man. No, Jesus promises us a guide: the Spirit of Truth. He will make sure that the Church comes to the correct understanding of the divine mysteries. He does not promise that it will not be a long, difficult journey at times, or that some people will not attempt to lead the Church down the wrong path, but he does promise that we will eventually be led to “all truth”.
For those interested in studying more about the development of doctrine, I recommend two works:
An Essay on the Development of Christian Doctrine – John Henry Cardinal Newman
The Christian Tradition – Jaroslav Pelikan (a five-volume series; link is to the first volume)