Gotta say its absolutely buckwild that some people take "lean not on your own understanding" to be like "dont at all read the Bible because what if you get IDEAS". That... does not sound healthy.
You say that and yet that was a common thing that priests told parishioners pre-Vatican II.
Certainly, today we ought to have a more vivid awareness that there exists an unbroken continuity in the life of the Church —in the proclamation of God, in the celebration of the sacraments— which reaches down to us and which we call Tradition. It gives us the guarantee that what we believe is the original message of Christ preached by the Apostles. The core of the original proclamation is the event of the Passion, Death, and Resurrection of the Lord Jesus, from which flows the entire patrimony of the faith. In this way, while Sacred Scripture contains the Word of God, the Church’s Tradition preserves and faithfully and integrally transmits it, so that men and women of every age may have access to its immense riches and be enriched by its treasures. Thus, the Church "perpetuates and transmits to every generation, in her doctrine, her life, and her worship, all that she herself is, all that she believes" [Dei Verbum, §8a].
Cardinal Robert Sarah (An Appeal to Unity), trans. Diana Montagna
Scripture is not revelation. Neither is tradition.
The Catholic Church teaches that tradition is not a source of revelation, but one way in which the perfect revelation of Jesus Christ is transmitted. Likewise, Scripture is not revelation, but the handing on of revelation in a particular and special way.
Below the break, I’ve excerpted Dei Verbum 2, 7-8 , but the point is made even more clearly in the chapter headings for chapter I (Revelation itself) and chapter II (handing on divine revelation). It helps to know Latin: traditio = handing on, handing over, giving across.
CHAPTER I REVELATION ITSELF
2. In His goodness and wisdom God chose to reveal Himself and to make known to us the hidden purpose of His will (see Eph. 1:9) by which through Christ, the Word made flesh, man might in the Holy Spirit have access to the Father and come to share in the divine nature (see Eph. 2:18; 2 Peter 1:4). Through this revelation, therefore, the invisible God (see Col. 1;15, 1 Tim. 1:17) out of the abundance of His love speaks to men as friends (see Ex. 33:11; John 15:14-15) and lives among them (see Bar. 3:38), so that He may invite and take them into fellowship with Himself. This plan of revelation is realized by deeds and words having an inner unity: the deeds wrought by God in the history of salvation manifest and confirm the teaching and realities signified by the words, while the words proclaim the deeds and clarify the mystery contained in them. By this revelation then, the deepest truth about God and the salvation of man shines out for our sake in Christ, who is both the mediator and the fullness of all revelation... For this reason Jesus perfected revelation by fulfilling it through his whole work of making Himself present and manifesting Himself: through His words and deeds, His signs and wonders, but especially through His death and glorious resurrection from the dead and final sending of the Spirit of truth. Moreover He confirmed with divine testimony what revelation proclaimed, that God is with us to free us from the darkness of sin and death, and to raise us up to life eternal.
The Christian dispensation, therefore, as the new and definitive covenant, will never pass away and we now await no further new public revelation before the glorious manifestation of our Lord Jesus Christ (see 1 Tim. 6:14 and Tit. 2:13)...
CHAPTER II HANDING ON DIVINE REVELATION
7. In His gracious goodness, God has seen to it that what He had revealed for the salvation of all nations would abide perpetually in its full integrity and be handed on to all generations. Therefore Christ the Lord in whom the full revelation of the supreme God is brought to completion (see 2 Cor. 1:20; 3:13; 4:6), commissioned the Apostles to preach to all men that Gospel which is the source of all saving truth and moral teaching, (1) and to impart to them heavenly gifts. This Gospel had been promised in former times through the prophets, and Christ Himself had fulfilled it and promulgated it with His lips. This commission was faithfully fulfilled by the Apostles who, by their oral preaching, by example, and by observances handed on what they had received from the lips of Christ, from living with Him, and from what He did, or what they had learned through the prompting of the Holy Spirit. The commission was fulfilled, too, by those Apostles and apostolic men who under the inspiration of the same Holy Spirit committed the message of salvation to writing. (2)
But in order to keep the Gospel forever whole and alive within the Church, the Apostles left bishops as their successors, "handing over" to them "the authority to teach in their own place."(3) This sacred tradition, therefore, and Sacred Scripture of both the Old and New Testaments are like a mirror in which the pilgrim Church on earth looks at God, from whom she has received everything, until she is brought finally to see Him as He is, face to face (see 1 John 3:2).
8. And so the apostolic preaching, which is expressed in a special way in the inspired books, was to be preserved by an unending succession of preachers until the end of time. Therefore the Apostles, handing on what they themselves had received, warn the faithful to hold fast to the traditions which they have learned either by word of mouth or by letter (see 2 Thess. 2:15), and to fight in defense of the faith handed on once and for all (see Jude 1:3) (4) Now what was handed on by the Apostles includes everything which contributes toward the holiness of life and increase in faith of the peoples of God; and so the Church, in her teaching, life and worship, perpetuates and hands on to all generations all that she herself is, all that she believes...
Dr. Kwasniewski, 6 Important truths about Scripture for Advent:
“The Church opens the Bible for us:
There exists a close connection and communication between Sacred Tradition and Sacred Scripture. For both of them, flowing from the same divine wellspring, in a certain way merge into a unity and tend toward the same end. For Sacred Scripture is the word of God inasmuch as it is consigned to writing under the inspiration of the divine Spirit, while Sacred Tradition takes the word of God entrusted by Christ the Lord and the Holy Spirit to the Apostles, and hands it on to their successors in its full purity . . . Sacred Tradition and Sacred Scripture form one sacred deposit of the word of God, committed to the Church. ... [T]he task of authentically interpreting the word of God, whether written or handed on, has been entrusted exclusively to the living teaching office [Magisterium] of the Church, whose authority is exercised in the name of Jesus Christ. (Dei Verbum 9–10)
“History has borne abundant witness to this last claim: wherever the authority of the Catholic Church has c assailed or rejected, the authority of Scripture has grown progressively weaker, in some instances disappearing altogether. Conversely, wherever Scripture is accepted as divine truth, there is an awareness, bright or dim, of some supernatural reality called “the Church,” and a desire to belong to it, as if implicitly recognizing that a book by itself doesn’t make a religion. John Henry Newman made a similar observation in regard to Marian devotion, saying in his Letter to Pusey that, as a matter of historical fact, wherever the cultus of the Virgin Mary was abandoned, sooner or later faith in the very divinity of Christ was abandoned. Because of the ineffable mystery of the Incarnation, Mother and Son can never be parted, no more than Father and Son.”
For the words of God, expressed in human language, have been made like human discourse, just as the Word of the eternal Father, when He took to Himself the flesh of human weakness, was in every way made like men.
What parts of the Old Testament law are Catholics supposed to abide by? How do we know that?
There are different answers to this, depending on how one takes the question.
1. Anyone who is not circumcised under the Law or whose father is not circumcised is not subject to Mosaic Law. So almost zero Catholics are under the Law according to the Law itself.
2. The Old Testament, including the first laws and sacrificial system, is nonetheless part of God's revelation (cf. Romans 3:2). So it's not just to be set aside.
3. Christians should regard the Old Testament, including the Law, as God's pedagogy. (I devote several chapters of my book to this idea.) It's an earlier stage of God's formation of a people so that some of them might be able to receive the fullness of revelation in Jesus, God’s Thought made flesh.
Vatican II, Dei Verbum 15: “The principal purpose to which the plan of the old covenant was directed was to prepare for the coming of Christ, the redeemer of all and of the messianic kingdom, to announce this coming by prophecy (see Luke 24:44; John 5:39; 1 Peter 1:10), and to indicate its meaning through various types (see 1 Cor. 10:12). Now the books of the Old Testament, in accordance with the state of mankind before the time of salvation established by Christ, reveal to all men the knowledge of God and of man and the ways in which God, just and merciful, deals with men. These books, though they also contain some things which are incomplete and temporary, nevertheless show us true divine pedagogy. These same books, then, give expression to a lively sense of God, contain a store of sublime teachings about God, sound wisdom about human life, and a wonderful treasury of prayers, and in them the mystery of our salvation is present in a hidden way. Christians should receive them with reverence.”
4. Baptism places us under the Law of Christ, and therefore under the canon law of the Church. The Church determines how to put God's revelation, including Old Testament revelation, into practice. For instance, the Church has replaced Saturday as the Sabbath with Sunday, preserving the Old Testament idea of a day consecrated to God, but moving it to the day of the Resurrection.
You can read more in Dei Verbum. But that's the basic idea: we read and study the OT, but are under the law of the Church, obedience to which is sufficient for our salvation.
The Church does not live on herself but on the Gospel, and in the Gospel always and ever anew finds the directions for her journey. This is a point that every Christian must understand and apply to himself or herself: only those who first listen to the Word can become preachers of it.
Indeed, they must not teach their own wisdom but the wisdom of God, which often appears to be foolishness in the eyes of the world (cf. I Cor 1: 23).
Pope Benedict XVI, September 2005, Address to the Participants in the international Congress to Commemorate the 40th Anniversary of the Dogmatic Constitution on Divine Revelation ‘Dei Verbum.’
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