The opening verse of the letter to the Hebrews begins like this: Long ago God spoke to our ancestors in many and various ways by the prophets (Heb 1.1). In this respect I wish to emphasize the role of the past in Christian thinking.
I think it was C.S. Lewis who spoke of "chronological snobbery," a kind of arrogant presumption of the falsehood of all things connected with the past and with tradition. The chronological snob thinks that the relative age or even antiquity of a certain position or opinion speaks against the likelihood of its truth. This ma be simply because it is past, or it may be motivated by some kind of metanarrative mythology of the progress of humanity, or whatever. In any case, chronological snobbery is an eminently un-Christian attitude.
The author of the letter affirms that God spoke to their ancestors in the past. This is enough to speak against any exaggerated chronological snobbery, whether secularist or Christian of the quasi-Marcionite sort, which would deny the theology of the Old Testament. God did speak to Abraham, he did speak to Moses, he did speak to Samuel and David and the rest -- that is what the author here is telling us. Therefore we ought to be careful to listen to that voice of God as well.
This is not to deny that there may have been some misconceptions or misunderstandings. Even we who have received the revelation of Jesus Christ misunderstand and misinterpret. But at the same time we cannot simply deny flatly any kind of theological knowledge or substantial revelation to the people of God of antiquity.
Stăniloae speaks of the importance and function of the tradition in preserving the revelation given long ago to our ancestors. Just as the call of Abraham had to be preserved throughout the generations in order to make it into our Bibles, so also the message and truth of Jesus Christ had to be preserved through the testimony of the apostles and the subsequent tradition of the church which sought to preserve it:
The Church is the milieu in which the content of Scripture or of revelation is imparted through tradition. Scripture or revelation need tradition as a means of activating their content, and they need the Church as the practicing subject of tradition and the milieu where the content of Scripture or revelation is imparted (The Experience of God: Orthodox Dogmatic Theology, p. 54).
The function of tradition is to preserve the message received and the proper interpretation thereof. Too often Christians assume that long ago God did not speak, and that a complete rupture with the long tradition of Christian theology can be safely made. The truth is something else altogether: apart from the testimony of the Old Testament and the surviving Hebrew traditions, we have no access to the truths of God's call of Abraham, the election of the Israelite people, and the background story which motivated and informed the announcement of the gospel of Christ's coming; apart from the testimony and tradition of the Christian church throughout the ages, we have no access the genuine meaning of the revelation of God given in Jesus Christ and passed down by the apostles. We cannot be Christians in or from a vacuum; we cannot be chronological snobs.
Stăniloae goes so far as to identify the church with the tradition: The Church appears simultaneously with tradition because tradition is revelation incorporated into a community of believing people (p. 55). A break from tradition is tantamount to a rejection of the church, just as a rejection of the story of Abraham and the prophets would be a break from Hebrew religion as such.