Development of Doctrine
Development is how Catholics try to explain away their doctrinal novelties
Christian doctrine was given once and for all, completely developed, by Jesus Christ
Development of doctrine is common to all kinds of Christians; it happened in history with regard to doctrines agreed upon by all, and it is also seen in the Bible.
The Catholic Church holds that there was one apostolic deposit, given by Jesus Christ to the apostles, and that there has been no essential change in that. The Catholic Church preserves this apostolic deposit (Jude 3), and is the Guardian of it. But, on the other hand, there is a growth in clarity of those truths, and men’s understanding increases. One must keep this distinction in mind when discussing development.
Protestants believe in progressive revelation. Reading Genesis is a lot different from reading, say, John or Colossians. It is obvious that great development of the thought and the theology occurs. As an example, one could analyze the idea of faith or salvation. First, the Bible presents the Abrahamic Covenant, which is basically Abraham believing in God, and this being “reckoned unto him righteousness.” A little later on, we see the notion of the chosen people, which is somewhat like election, or enabling grace from God. In other words, it’s unmerited. God chose them and gave them grace for His purposes. The Law and the commandments were given to preserve this people.
Then God reveals the eternal Davidic Covenant to David, and we slowly see in the Bible a notion of the Messiah, and in Isaiah 53, the “suffering servant” – which predicted Jesus’ Passion. This is all development of doctrine: all the way through the Old Testament, to the gospel being announced, with John the Baptist and Jesus Himself, and even then Jesus said that He came not to “abolish” the Law but to “fulfil” it (Matt. 5:17).
In the Christian era, doctrines continue to develop. The Church especially pondered more deeply the doctrine of Christ in response to heretics; for example, at the council of Chalcedon in 451, which decreed the notion of the Two Natures of Christ or Hypostatic Union: Jesus is both God and Man. That was in response to the Monophysite heresy, which held that Jesus had one nature. Other doctrines which clearly developed were the afterlife, the Holy Spirit, the equality of Jews and Gentiles, bodily resurrection, Christ’s sacrifice as a development of the sacrifice of lambs, etc. No doctrine emerges in the Bible complete with no further need of development.
Granted, some doctrines have developed. But Catholics go beyond the Bible when they develop doctrines, such as Mary and purgatory. There is no biblical check on the development, so that it can go off into false teaching and the traditions of men.
Reply to Objection
There is more evidence for acceptance of the doctrine of purgatory in the Church fathers than for original sin (accepted by all Christians). One cannot have it both ways. If purgatory is unacceptable because it developed “late,” then original sin must be rejected with it. Catholics can give plenty of biblical evidences of purgatory. At the time the Marian doctrines were developing, so were things like the canon of Scripture and Christology and the Trinity. If those things could develop many centuries after Christ, why is it objectionable for the Marian doctrines or eucharistic theology to also do so? The Church decided what was a true development and what wasn’t.
The Bible indicates something like development of doctrine, too (Jn. 14:26, 16:13; 1 Cor. 2:9-16; Gal. 4:4; Eph. 1:10; 4:12-16). The Church is called the “Body of Christ” (e.g., Eph. 1:22-23), and is compared to a seed that grows into a tree (Matt. 13:31-32). Seeds and bodies grow and expand. This is development of doctrine.
Within the limits of the Jewish theocracy and Catholic Christianity Augustin admits the idea of historical development or a gradual progress from a lower to higher grades of knowledge, yet always in harmony with Catholic truth. He would not allow revolutions and radical changes or different types of Christianity. (Philip Schaff, Protestant Church historian, Introduction to St. Augustine’s City of God, in the 38-volume set of the Church fathers, edited by himself, December 10, 1886)
How can an unchanging system survive the continual increase of knowledge? . . . Change is not progress unless the core remains unchanged. A small oak grows into a big oak; if it became a beech, that would not be growth, but mere change . . . There is a great difference between counting apples and arriving at the mathematical formulae of modern physics. But the multiplication table is used in both and does not grow out of date. In other words, whenever there is real progress in knowledge, there is some knowledge that is not superseded. Indeed, the very possibility of progress demands that there should be an unchanging element . . . I take it we should all agree to find this . . . in the simple rules of mathematics. I would also add to these the primary principles of morality. And I would also add the fundamental doctrines of Christianity . . . I claim that the positive historical statements made by Christianity have the power, elsewhere found chiefly in formal principles, of receiving, without intrinsic change, the increasing complexity of meaning which increasing knowledge puts into them . . . Like mathematics, religion can grow from within, or decay . . . But, like mathematics, it remains simply itself, capable of being applied to any new theory. (C. S. Lewis, Anglican apologist, God in the Dock, edited by Walter Hooper, Grand Rapids, Michigan: Eerdmans, 1970, 44-47. From “Dogma and the Universe,” The Guardian, March 19, 1943, 96 / March 26, 1943, 104, 107)
Further introductory materials on development:
(originally 8-30-06, intended for but not included in my book, The One-Minute Apologist  )
Photo credit: An Oxford caricature of John Henry Newman, 1840: five years before he wrote his famous Essay on the Development of Christian Doctrine and was received into the Catholic Church [public domain / Wikimedia Commons]