THE BASIS OF CHRISTIAN DOCTRINE
On what is Christianity based?  This may seem like a very simple question, but it isn't as easy as it looks.  What are we, as Christians, to believe?  Here are some possibilities.
ALTERNATIVE ONE:  We cannot be certain of any doctrine of Christianity, even if it is explicitly contained in the Bible, because we cannot be certain of the Bible's inerrency.  Thus, we cannot claim to be certain of the Divinity of Christ or the Resurrection, since these things maybe have been added to the gospel accounts at a later time.

THE CATCH: If you cannot be sure of anything about your religion, you cannot be said to believe anything about it.  Alternative One is really agnosticism (or, in moral matters, relativism), though it often goes by the name of "liberal Christianity".  This theory leaves us floundering in a sea of humanist philosophy and feel-good catchphrases, without a rock to stand on.
ALTERNATIVE TWO:  We can be certain only of what is actually stated in the Bible, but the Bible itself is infallible.  That is, it is inspired by God and free of error. It is our sole authority in matters of faith and morals.  This idea is called "sola scriptura" and it dates from the Reformation; in fact, it was one of the two great arguments of the Reformation.

CATCH #1:  How do you know which books of the Bible are infalilble and which are not?  The Bible itself does not contain any list of inspired books.  It has been said that with this argument, you have "a fallible list of infallible books". In other words, maybe some of the books in your Bible AREN'T inspired, in which case, you could be believing things which are wrong.  Maybe there are books which ARE inspired, but which are not in your Bible, which means there may be things which you should believe which you don't.

In fact, there is a disagreement on which books are inspired.  Most of the world's Christians use the Old Testament based on the Septuagint, a Greek translation of the Old Testament which includes forty-six books.  Most Protestants, however, use the Old Testament based on the Palistinian canon, which has only thirty-nine books.  This is the version which has been favored by most Jews since about 70 A.D., though there are some Ethiopian Jews who have always used the longer Old Testament.

Which Bible is right? How do we know?  If the Bible is the only source of authority, you really do not know what to believe, because you don't know what the Bible is!

CATCH #2:  What does the Bible mean?  The Reformers claimed that the Bible is easy to understand, that the Church is not needed to interpret or explain it.  If this is true, why are there so many different ideas about what Christ meant when he said: "This is my body"? Catholics, Orthodox Christians, Lutherans and Episcopalians all take him literally, but many Protestants do not.  Likewise, some Christians believe that when Jesus said "Unless you are born of the water and the spirit, you cannot enter the Kingdom of God" He meant that Baptism with water is normally a necessary part of salvation.  Others think he meant that only a spiritual baptism is necessary, and that the water is just a sign.  Most Christians believe that there is one God consisting of three Divine Persons: Father, Son, and Spirit.  Others reject the doctrine of the Trinity, and both sides cite scriptural passages to prove their point. 

Some people say that the Holy Spirit guides each of us in interpreting the Bible, but if this is true, why has the Holy Spirit guided so many people in so many different directions?

CATCH #3:  The biggest catch of all.  The idea that the Bible is our only authority, and the only guide to doctrine which we need is not found in the Bible.  As former Presbyterian minister Scott Hahn puts it:  "Sola Scriptura is unscriptural!" And that makes it self-defeating.
ALTERNATIVE THREE:  The Bible is not the only source of authority: the Church also has authority, and is protected from error by the Holy Spirit, just as the Scriptures themselves were protected during their writing.

Christ gave the Church her mission in Matthew 28:18-20:

"All power is given unto me in heaven and in earth.  Go therefore and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost: teaching them to observe all things whatsoever I have commanded you; and lo, I am with you always, even unto the end of the world."

In Matthew 16:18, Christ promised that His Church would not fail.  He promised, too, that he would send the Holy Ghost to lead the Church "into all truth" (John 16:13).  So we see that the Church has the authority to teach and to administer the sacraments.  We know that we can trust the Church because Christ promised that it would not fail, because the Holy Spirit guides the Church to all truth, and because Christ promised to stay with us always.


PLUSES:
1) If the Church is infallible, this means that we can trust our canon of the Bible, because the Church set the canon for both the New and Old Testaments.  The Council of Rome in 382 affirmed the same canon used today by Roman Catholics.  All Christians (with the exception of a few Eastern Churches, which use an even longer canon!) used this Bible until the Reformation, when some books were removed from the Old Testament.  Part of the reason they were removed by Protestants is that there were no Hebrew language copies of these books, and that the European Jews id not use them. What the Reformers did not know was that there were Jews in Africa who had always considered these books to be inspiried, that the Apostles used the Septuagint rather than the Palistinian canon, sometimes making references to books not found in the Palistinian canon, AND that there were Hebrew copies of some of these "hidden" books waiting to be found.

Another reason the deuterocanonical books were removed is that some of them (Tobit and 2 Maccabees, in particular) did not agree with the Reformer's theology.  However, we base doctrine on Scripture, not vice versa.  As Paul says: "All Scripture is given by the inspiration of God, and is profitable for doctrine, for reproof, for correction, for instruction in rightousness."  The Scripture Paul used was the Septuagint.  He makes reference to an incident in 2 Maccabees, and paraphrases from the book of Wisdom.  Why, then, wouldn't his statement about the inspiration of Scripture cover the Deuterocanonical books as well as those found only in the Palistinian canon?

2)  If the Church is infallible, we have some guide as to how to interpret the Bible.  We don't have to "reinvent the wheel", as Scott Hahn put it, in interpreting the Bible on our own.  We have some framework of doctrine on which we can base our personal studies of Scripture and theology. 

In general: We know what to believe, because the Church is "the pillar and ground of truth" (1 Timothy 3:15). 

THE CATCH:  This theory means accepting an outside authority.  People have a hard time doing this!
A LOGICAL EXTENSION OF ALTERNATIVE THREE:
In Matthew 16: 18, Christ says that the Church is built on Peter.  In fact, He changed Peter's name from Simon (he heard) to Peter (rock) when making this statement.  In the Bible, a name change always accompanies a change in position.  Thus, Abram became Abraham when God made a covenant with him.  Likewise, Saul became Paul when he converted to Christianity.  Now Simon becomes Peter, and he is given "the keys to the kingdom of heaven" and the power to bind and loose on Heaven and on Earth. 

Later, Christ says that He will pray for Peter that his "faith may not fail."  He also tells Peter to strengthen his brothers (Luke 22:32).  And in John 13:15-17, He instructs Peter to "feed my sheep."  Now, Christ referred to Himself as the Good Shepherd.  He referred to His followers, to the Church, as a flock.  When He intructs Peter to feed His sheep, He is clearly placing Peter in a position of surrogate authority.  Christ is the head of the Church, there is no doubt about that, but there can be little doubt either that He appointed Peter as the earthly head of the Church.

But Peter died.  Was the young Church left without a leader?  Why would Christ do that?  Why did He give Peter a position of authority over the other apostles (the first bishops) if it was only to last for a few years?  Christ's Church, we know, will last until the end of the world.  His mission --to spread the Good News everywhere-- has not yet been fulfilled.  We still need someone to feed the sheep.  We need a successor for Peter, leader of the apostles.

That successor is the Pope.  There is a line of pontiffs going all the way back to Peter, first leader of the Apostles and first Bishop of Rome.  John Paul II is the current Pope. And because of Christ's promise in Matthew 16:18 and in John 14:26, we know that when the Pope announces an official doctrine, speaking as the successor of Peter, that doctrine is protected from error by the Holy Spirit.  In other words, under those specific circumstances, the Pope speaks infallibly.  This does not mean that all of his decisions are automatically right.  Popes have made mistakes.  This does not mean that he is a perfect man.  All people sin, and there have been corrupt Popes.  But there has NEVER been a Pope who promulgated as infallible doctrine any thing that is heretical.  That has never happened.  We have Christ's assurance that it never will.

Only in the Catholic Church is such assurance found, for no other Church has the Pope or the Magisterium of Bishops in union with him.  That is why so many thoughtful Christians call Rome Home!

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BIBLICAL EVIDENCE FOR CATHOLICISM.