The anti-Catholic world is full of anti-Catholic myths - it created them, it lives on them, and it seemingly constantly recycles them and expands them into ever new territories and heights.
It is necessary for this mythology (and I use the word here in the negative sense, to indicate things that are not true) to exist because without it the truths of the Catholic faith would shine far too brightly for the tolerance of many. These myths keep those who due to innocent ignorance do not know the Church away from her and are also the primary tool used by those who are capable of knowing better but not interested in doing so to justify their own anti-Catholic sentiments.
I'm intentionally not including *all* of them here, but these are the major ones, in no particular order.
Catholics "Worship" the Saints
This belief is grounded in a complete misunderstanding of "worship" vs. "honor", and, like all Protestant misconceptions, can only arise where there is a lack of knowledge of both Scripture and Christian history.
Catholics "Worship" Mary
Catholics "Worship" Bread and "Re-Crucify" Christ in the Mass
Actually, Christians have been practicing the Holy Sacrifice of the Mass since birth of the Church at Pentacost. Christ commanded His apostles (who commanded their successors) to continue to re-present His Last Supper (which is the same Sacrifice He offered once & for all on Calvary) and told those who would not consume His Body & Blood that they would not "have life".
I cover the basis of the Mass in Scripture and Tradition in this extensive essay: http://www.catholicthinker.net/the-eucharist/
Purgatory Is [Another] "Catholic Invention"
The Catholic Church Added Books to the Bible
Such a completely preposterous accusation, this one. The deuterocanonical books were part of "the Bible" from the moment the Bible existed as a single work - when the Catholic Church defined the canon, that is. Martin Luther removed these books from the Bible because they contain some very strong evidence for Catholic theology that he didn't like. (And, of course, he also spat upon other, New Testament, books that he didn't care for, such as James and Revelation, even relegating the former to a special section of his Bible since he deemed it unworthy. Never mind that it had always been regarded as divinely inspired - for Luther, private interpretation extended to the very definition of the canon (as it now does implicitly for Protestants in general who have followed his lead on the deuterocanonical books).)
There are some notes on the this subject in the above essay on Purgatory; an honest Google search will also uncover the truth of the matter.
The Catholic Church Teaches "Works-Based" Salvation
See this document.
The Catholic Church Has Become "Pagan" And Is the Very Whore of Babylon of Revelation
Though it's perhaps better to decline to even acknowledge to this sort of thing with any response, EWTN has a good, short article on the idiotic Whore of Babylon "argument":
Catholics Have No Personal Relationship With Christ
This sort of "argument" is revealed with a cursory look to be nothing other than spite and prejudice with absolutely nothing behind it.
Anyone who knows anything about Catholic doctrine knows that the Church teaches the divinity of Christ, the Incarnation, the Atonement, and the Resurrection (the Church defined all these teachings that Protestants also accept) and that love of Christ and devotion to Christ are at the very center of Catholic worship and always have been.
In making such a charge, the fundamentalist is implying that he knows the hearts of others: an arrogant and sinful thing to assert. Furthermore, he's essentially attempting to prove a negative (with no evidence at all), by stating that no Catholics have any "personal relationship" with Christ. (That's nearly always how it's phrased: they don't say "most Catholics" or "a lot of Catholics" or even say "Catholic teaching doesn't foster devotion to Christ" - they just make a completely, all-inclusive statement.)
For good Catholics, Christ is the center of life. And being united to Christ physically in the Sacrament of the Eucharist is the most deep and intimate union with Him that is possible outside of Paradise.
Calling Priests "Father" is Unbiblical
Only by pitting Scripture against Scripture and also ignoring one's own life can one conclude that it is "Unbiblical" to call someone father. Of course, Christ did say "Call no man father" and "Call no man teacher" - did He really mean, literally, to never use these titles for anyone, ever? If so, how can it be that Scripture Itself uses them so frequently? And how can it be that virtually all Protestants call their fathers "father" and their teachers "teacher"?
See this synopsis of the use of these titles in Scripture:
Only someone who knows their Bible very poorly and also can seemingly not think or reason could make such an argument. (Or, someone who is so blinded by prejudice they are able to ignore many basic facts.)
The Inquisition Killed Millions
The first thing that might noted when someone makes the (usually implicit) argument "The Catholic Church can't be the truth Church, or even "good", because it's done these terrible things" is that the argument itself belies a core misunderstanding of the nature of Christ's Church: the Church is not the people in the Church. The Church is pure and holy in its teachings and its sacraments; nobody ever claimed that all of its members or even all of its clergy are perfect and sinless, and obviously that would be a completely ridiculous thing to claim. The evil actions of the Inquisition were the actions of individual churchmen, not of the Church.
Am I saying that the Inquisition itself was not evil? In the sense that its purpose was to rout out heresy, no, it certainly was not. The Bible supports the notion very explicitly:
"If there is found among you, within any of your towns which the Lord your God gives you, a man or woman who does what is evil in the sight of the Lord your God, in transgressing his covenant, and has gone and served other gods and worshiped them, or the sun or the moon or any of the host of heaven, which I have forbidden, and it is told you and you hear of it; then you shall inquire diligently [note that phrase: "inquire diligently"], and if it is true and certain that such an abominable thing has been done in Israel, then you shall bring forth to your gates that man or woman who has done this evil thing, and you shall stone that man or woman to death with stones." (Deuteronomy 17:2–5)
And, of course, Protestants have had their own Inquisitions - which, according to the best historical data now available, very likely killed more people than the Spanish Inquisition, an even that has become completely distorted by falsehoods:
It is likely that the Protestant "witch" burnings in Germany alone killed more people (the vast majority of which were almost certainly not practicing witchcraft) than the various actions of the Inquisition in Catholic Europe.
It's clear that there's simply no point at all to be had here against the Catholic Church itself as a holy and pure institution by Protestants. If there were abuses of power and sins committed in the course of the exercise of the Office of the Inquisition, those sins are on the heads of the Christians that committed them, not the Church.
The Catholic Church Teaches That Only Catholics Can Go to Heaven
This is false in the sense that Protestants use it because the dogma extra ecclesium nulla salus (There Is No Salvation Outside the Church), properly interpreted as by the Church, means essentially that all salvation flows through the Church and because of this it is possible for souls to be [imperfectly] mystically united with Her even without being visible members, and thus saved. (I can't fault Protestants heavily for not understanding this teaching because many Catholics (especially today when the faith is not taught properly) do not understand it either.)
Baptism (in the proper Trinitarian formula) unites every Christian at least imperfectly with the Catholic Church (whether or not it is known or acknowledged). This is why the Church has recognized Protestant baptism as valid since the dawn of Protestantism. At least until the point of knowingly and obstinately embracing formal heresy, such souls are Catholic and the grace of their baptism is certainly salvific.
In addition, the Church has declared in infallible teaching on several occasions that the baptism of desire (wishing to become a Christian) is potentially salvific and this is so even in the case of implicit baptism of desire - a soul that would seek the Church if she knew of its true nature. Such souls can be saved by obeying the natural law written on all hearts and seeking God honestly. The Church declares that no one who is not guilty of deliberate mortal sin will suffer eternal punishment.
So, while it is not true that only visible, practicing Catholics can be saved, by no means are there guarantees for those who knowingly reject the authority of the Church. Christ said to the apostles, "He who rejects you rejects Me".