Claim: The Roman Catholic Church says it never changes; yet it invents new doctrines which are contrary to the Bible / Objections to the Magisterium & Sacred Tradition
The objections put forward here are common amongst Protestants. It stems from their erroneous beliefs regarding Scripture and its place in the Christian life. These erroneous beliefs are together called Sola Scriptura, or Scripture alone. Sola Scriptura was divined by Martin Luther, using his private interpretation. Before Luther, no Christian ever believed in Sola Scriptura, but rather understood Scripture to be a part of the overall source from which we derive our Catholic teaching, called the Deposit of Faith.
Thus, the teachings which comprise Sola Scriptura say that Scripture is:
(1) the sole source of Christian doctrine,
(2) the sole norm of doctrine,
(3) the supreme, infallible and sole authority in the Church,
(4) that every single statement, doctrine, command, of the Bible calls for instant and unqualified acceptance, without the use of reason,
(5) sufficient, that is, that Scripture has no deficiencies to be supplied by oral tradition, pronouncements of the Roman Pontiff, Bishops, theologians or Councils,
(6) Perspicuous, that is, that the Scriptures sets forth all the doctrines on Christian faith and life in most clear terms that both the unlearned and learned can understand, and that Scripture needs not wait for any Pontiff, theologian or Council to make clear its teachings,
(7) its own authentic and infallible interpreter, that is, no human authority, or even reason, is needed to divine its true sense.
(8) That is it is the privilege and duty of all Christians to read and study the Scriptures,
(9) That every man can use his private interpretation to come to the knowledge of saving truth.
Every one of the nine sub-teachings of Sola Scriptura printed above are erroneous and dangerous. Numbers (4) and (7) specifically deny the need for reason when understanding or interpreting Scripture. Yet, the Catholic Church cautions us that we must use reason, firstly because we are given reason by God to understand, and secondly because Scripture is a product of both Divine and human reason. In addition, without reason to guide us, we end up with a mess of interpretations, as the Protestants have. Couple that with numbers (6), (8) and (9) which, joined together, say that even the unlearned man has the duty to study Scripture and privately interpret it, and you have a disastrous cocktail which can only lead to one thing: schism. And after that, when men become disillusioned with the manifold schisms and confusion as to which is true, indifferentism and then finally atheism.
Now, it must be understood that differing Protestant sects have slightly different views as to Sola Scriptura. For example, one may say the use of Councils, traditions, Church Fathers etc., are okay, as long as they are subject to the Scriptures (and one's interpretation of them), whilst others reject anything other than Scripture.
Whilst pondering on how to work out this Apologetics article, I stumbled across an article entitled Questions for Catholics on Sacred Tradition, by CARM, a Calvinist ministry. In its introduction, the author, the anti-Catholic Matt Slick, boasts how after posing these questions, "I do not believe that any Roman Catholic will answer them all." I wish to use these questions as a tool of providing a general answer to objections regarding Sacred Tradition, the Magisterium, etc. I shall use his format, albeit slightly adapted.
As there are 65 questions posed, this will mean that this article may be of some length, yet it may not be necessary to answer each question individually, as some original answers may also answer later questions. I shall break the article according to section, and each section shall be a fresh page. I shall link to each section as more are published.
Section I: Sacred Tradition
1] What exactly is Sacred Tradition?
Well, we have to ask what tradition is. The word tradition comes from the Latin traditio, meaning to hand on. Thus anything that is handed on, like the Bible or the Faith, is a tradition. Unfortunately for Protestants, even their particular creeds are traditional, because they are handed down from one generation to the next, whether in written form or orally. So, whether they like it or not, Protestants actually observe the very thing they oppose. In fact, the Bible itself is a product of tradition, since, for example, Moses records events that took place centuries before his birth. These events were orally handed down, protected by the Holy Spirit, until He moved Moses to finally record these oral traditions as written traditions.
Over the course of many centuries, God slowly revealed Himself to man in stages.  He began with Creation itself, then by the creation of our First Parents, Adam and Eve. Since then, God has revealed Himself over the centuries of Sacred History, and His Revelation is that He is a loving Father Who wishes us to be with Him in beatitude. The completion of Divine Revelation came in the Person of the Divine Word, Jesus Christ. After the death of St. John the Apostle, all public Revelation ceased, so that everything which God wished to reveal about Himself is now revealed, though it is not yet fully expounded, or made explicit. 
This complete Divine Revelation was given by Christ to the Church as the Deposit of Faith . A deposit is something entrusted to someone else, such as money entrusted by a person to a bank, for example. In a similar way, the Lord entrusted His Revelation to the Apostles, gave them authority and commissioned them to hand on (traditio) His Gospel to all men . By this, Sacred (or Apostolic) Tradition originates with Christ Himself, since He commanded the Apostles to hand on the Deposit to other men.
The Holy Apostles, guided by the Holy Spirit, fulfilled this commission in two ways:
- orally, by which the Apostles "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".
- in writing, "by those Apostles and apostolic men who under the inspiration of the same Holy Spirit committed the message of salvation to writing". 
Thus, the preaching of the Apostles was both oral and written. This is what St. Paul meant when he instructed the Thessalonian Church to "hold the traditions which you have learned, whether by word, or by our epistle". Of course, some of the written parts of Apostolic Tradition became the New Testament, that is, the received, inspired, Scriptures. The Apostles were preaching before they wrote anything down, meaning that the Catholic Church is older than the New Testament.
Those teachings of the Gospel never committed to writing under Divine Inspiration (in the form of Scripture), have been handed down within the Church from age to age in various ways, always protected by the Holy Spirit. Many are found in:
(a) the works of the Fathers of the Church, who lived before A.D. 750 and whose orthodoxy is specially recognised and celebrated by the Church: Pope St. Gregory the Great, the last of the Latin Fathers, died in A.D. 604; St. John Damascene, the last of the Greek Fathers, died in A.D. 749;
(b) The Acts of the Martyrs, which record in several instances the express doctrines for which the martyrs suffered;
(c) The Professions of Faith (such as the Creeds), and the teaching of both the Popes, in their capacity as Supreme Teacher, and the Ecumenical Councils of the Church;
(d) The practises and customs of the Universal Church, expressly, and in the first place, the Sacred Liturgy.
(e) And even through Christian art, which depict what we believed and how we worshipped over the centuries. 
However, this was not enough. The question arises: by what authority does the Apostolic Tradition, that is, all that the Apostles taught, come down to us? Well, the Lord already sorted that part out! The Apostles were to appoint successors, who they would teach and to whom they would pass the mantle of authority. These successors were the bishops. For example, St. Paul appointed St. Timothy as bishop of Ephesus, and St. Titus as archbishop of Crete. They in turn appointed successors, and on and on it goes. Every Catholic bishop today has Apostolic Succession, which they receive at their consecration as bishops.
Not only that, but "Revelation which as written or orally handed down is transmitted in its entirety through the legitimate succession of bishops and especially in the care of the Roman Pontiff himself", that is, the Roman Pontiff has the supreme duty above all to protect Revelation, and properly expound it, and at times, when prompted by the Holy Spirit, to define a doctrine ex cathedra.  In communion with him are the College of Bishops, who may as a College under the authority of the Pope, also define a doctrine ex cathedra. This is usually done in an Ecumenical Council. However, neither the Pope nor the bishops can define a new Revelation, nor accept any supposed new public Revelation. [13; 14]
1) What is tradition?
It is the handing on of teachings.
2) What is being handed on?
3) How is it handed on?
Through the preaching of the Apostles, the Sacred Scriptures, and various methods in the Church.
4) What is this tradition called?
5) Who founded Apostolic Tradition?
Christ, when He commanded the Apostles to hand on the Faith. However, it is the Apostles who executed this Tradition when they went forth to preach, hence this is why it is named after them. One may also call it Divine Tradition, since this is the means by which Christ Himself Willed that His Doctrines be handed on.
6) Who protects and teaches this tradition?
The Apostles and their Successors, the Bishops, through Apostolic Succession. In the first place, the Supreme Guardian and Teacher is the Roman Pontiff, the Successor of St. Peter.
7) Can the bishops or the Pope proclaim a new Revelation?
No. Neither the Pope nor the College of Bishops can proclaim a new Revelation, but only expound and define more clearly what Christ has already taught.
8) Who guides the Pope and the Bishops?
The Holy Spirit, the Spirit of Truth, Who was promised to the Church by Christ Himself.
9) Are there other traditions in the Church besides Apostolic Tradition?
Yes. The Church has other traditions, which, although not of Apostolic origin, are still binding upon the faithful. The rule is usually that if a tradition is practised for more than one hundred years, it is considered binding. Some of these traditions (also known as customs) include such things as fasting for forty days in Lent, how long to fast before receiving the Holy Eucharist, etc. Although these traditions are human in origin, their inspiration is given to the Holy Spirit, Who guides the Church in all Her activities. The Church has the authority to bind and loose the faithful according to the laws and customs which She has deemed, by the help of the Holy Spirit, to be most beneficial to the salvation of Catholics. Since the Church is the Mystical Body of Christ - and thus is Christ Himself on earth - we receive Her laws as if it where Christ Himself directly binding us. The Church cannot bind Catholics to a law that is detrimental to their salvation, since She is always guided by the Holy Spirit.
2] How is Sacred Tradition declared to be such in the Church?
In short, it is declared by Christ Who commanded the Apostles to hand on (traditio) Revelation to other men. However, He has given the Church the means to determine whether a teaching or practise is of Apostolic origin or not.
3] What is the means of the Church determining what is true Sacred Tradition?
See (a) - (e) above.
4] Did the Apostles intend for there to be Sacred Tradition or is Sacred Tradition something invented by the Church?
Since Tradition was the means by which Christ Himself willed for the Deposit to be handed on, it stands to reason that the Apostles did not have to intend for there to be such. And, likely, since it is of Divine Origin, Tradition is not an invention of the Church.
 - Catechism of the Catholic Church, para 54-64.
 - Catechism of the Catholic Church, para 65-67; Dei Verbum, para. 2: 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.
 - Catechism of the Catholic Church, para 66: Yet even if Revelation is already complete, it has not been made completely explicit; it remains for Christian faith gradually to grasp its full significance over the course of the centuries.
 - Catechism of the Catholic Church, para 84; Dei Verbum, para 10;
1 Tim 6:20: O Timothee, depositum custodi, devitans profanas vocum novitates, et oppositiones falsi nominis scientiae...[Latin Vulgate; emphasis mine];
2 Tim 1: 12-14: Ob quam causam etiam haec patior, sed non confundor. Scio enim cui credidi, et certus sum quia potens est depositum meum servare in illum diem. Formam habe sanorum verborum, quae a me audisti in fide, et in dilectione in Christo Jesu. Bonum depositum custodi per Spiritum Sanctum, qui habitat in nobis. [Latin Vulgate; emphasis mine]
 - Dei Verbum, para 7: 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, and to impart to them heavenly gifts.
 - Dei Verbum, para 7: 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.
- John 14:16-17; 14:26; 16:12-15: In these verses Christ promises the Spirit of truth to the Apostles to guide them into all truth. He even tells them that He has many more things to say to them, but cannot until later. Thus, the Spirit will come and reveal to them these teachings. This is a reference to the Church expounding Revelation. Christ knows that we cannot receive His Gospel all at once, so He kindly reveals it slowly, so that we may properly understand and believe. Some teachings, like the Holy Trinity, the Incarnation and the True Presence of Our Lord in the Eucharist are mysteries, that is, they cannot be comprehended by human reason, and thus will take longer to expound due to their mystical nature. For example, the Dogma of the Holy Trinity took some 300 years to define, and even then it was still being defined in detail! So profound and mystical is the Lord's heavenly Word, that even after two millennia expounding it, Holy Mother Church still does not fully comprehend, and most likely has not made even a dent in Divine Revelation. The Church could spend eternity just meditating on one teaching, so profound it is!
 - 2 Thessalonians 2:14.
 - Sacred Scripture Depends on Sacred Tradition, Catholic Answers, para 5.
- John 21:25: In this verse, St. John reminds us that not everything Jesus did was written down, because such a record would be so voluminous, not even the whole face of the earth could store it. Thus, other means of transmitting the Gospel were used, such as the Sacred Liturgy, Christian iconography and the like. In addition, it must be remembered that most Christians for c. 1900 years were illiterate. Thus, the use of art and Liturgy were the primary instruments through which the Church taught the people. A Catholic knew his faith through the Mass and the Liturgy and the icons and statues in his Church, not through the written word. This is why the Sacred Liturgy recreates many Biblical events, so that the illiterate Christian could re-play the very events recorded in Scripture. So, for example, when Christ enters Jerusalem on Palm Sunday; it becomes a physical celebration in which Catholics would carry blessed palms from one Church to another, singing Latin chants, and recreating the Entry into Jerusalem. Thus, even though they could not read the Scriptural account, they could participate in it by their actions and chants. Even today, most Catholics still get their understanding of the Gospel from the Liturgy. Thus, contrary to Protestant assertion, Christ could not have commanded His disciples to read the Scriptures, since such a command would have been an unreasonable burden upon most Christians, who could neither afford monies nor time to literacy. At least for Catholics, Christ is not so heartless as to command that which He knew would be unattainable for c. 1900 years!
 - Dei Verbum, para. 7: 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."
- Dei Verbum, para. 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.
 - Cf. Catechism of the Catholic Church, paras. 1555 & 1556.
 - Lumen Gentium, para. 25.
 - Lumen Gentium, para. 25: And this is the infallibility which the Roman Pontiff, the head of the college of bishops, enjoys in virtue of his office, when, as the supreme shepherd and teacher of all the faithful, who confirms his brethren in their faith, by a definitive act he proclaims a doctrine of faith or morals. And therefore his definitions, of themselves, and not from the consent of the Church, are justly styled irreformable, since they are pronounced with the assistance of the Holy Spirit, promised to him in blessed Peter, and therefore they need no approval of others, nor do they allow an appeal to any other judgment. For then the Roman Pontiff is not pronouncing judgment as a private person, but as the supreme teacher of the universal Church, in whom the charism of infallibility of the Church itself is individually present, he is expounding or defending a doctrine of Catholic faith.
 - Lumen Gentium, para. 25: The Roman Pontiff and the bishops, in view of their office and the importance of the matter, by fitting means diligently strive to inquire properly into that revelation and to give apt expression to its contents; but a new public revelation they do not accept as pertaining to the divine deposit of faith.
 - Pastor Aeternus, Vatican I: For the Holy Spirit was promised to the Successors of Peter not so that they might, by His revelation, make known some new doctrine, but that, by His assistance, they might religiously guard and faithfully expound the Revelation or Deposit of Faith transmitted by the Apostles. Indeed, their Apostolic teaching was embraced by all the venerable Fathers and reverenced and followed by all the holy orthodox Doctors, for they knew very well that this See of St. Peter always remains unblemished by any error, in accordance with the Divine Promise of our Lord and Saviour to the Prince of His disciples: "I have prayed for you that your faith may not fail; and when you have turned again, strengthen your brethren."