Although there is more heresy in the Catholic Church than there is sand in the desert, there are many oases of truth, too. Chief among these is its historical commitment to the doctrine of the Trinity. Although Pope Francis is shockingly comfortable referring to the Holy Spirit as "it", rather than the more appropriate "He", the Catholic Church still affirms that there is one God, but He exists in three separate, co-equal persons: The Father, the Son, and the Holy Spirit.
It is, however, no secret that the Catholic Church frequently robs God of His glory, blaspheming Him by applying His titles and attributes to other decidedly non-divine beings. Most notable is Catholic Mariology. Although they call it "veneration", Catholics, at least assuming they follow the official teachings of their Church, worship Mary. They will deny it, but given that the Bible even says your belly can be your god (Philippians 3:18-19), I see no reason to deny the idolatry of bowing to statues.
But this article is not intended to expose the specific blasphemies of the Catholic Church. Rather, the point of this article is to address the development thereof. See, contrary to Catholic assertion, there was no consistent string of Catholic tradition from the day Christ built His Church upon Peter until some devil named Martin Luther popped up 1500 years later. Rather, the unique doctrines of the modern Catholic Church developed over time, and in some cases, we can even identify exactly when those doctrines first became Catholic dogma. The Eucharist, for example, was not officially codified into Catholicism until the Great Eucharistic Controversy, which began in the mid 800s A.D. Purgatory, the Celibacy of the Clergy, the Marian dogmas, even the Papacy, were all absent from the early Church, and in some cases were even initially anathematised.
More educated Catholics have known and affirmed this fact for quite some time. A noteworthy example is 19th century Cardinal John Henry Newman, who is particularly famous for his quote "To be deep in history is to cease to be Protestant". Of course, now that he, himself, is history, he wishes he was "Protestant". Yet, during his life, he never had such wisdom. Instead, noticing the simple fact that the earliest Church were absolutely not Catholic, he came up with a theory called "Development of Doctrine".
The Development of Doctrine maintains that although modern Catholic doctrine is not found explicitly recorded in Scripture, nor in the writings of the so-called Church "Fathers" (upon whom Catholicism places far too much emphasis, at least when it's convenient for them), they are nevertheless found implicitly. Thus, the development of Catholic doctrine, rather than being a perversion of the faith, is really just the faith growing in maturity. He uses the analogy of an acorn to argue that such a development is necessary. While an acorn that transforms into a walnut is a mutation, an acorn that never develops into an oak tree is dead. Thus, Newman argues that such developments are logically inevitable.
There are a range of problems with this argument, starting with the simple fact that Scripture straight up denies it, and in a book written by a man whose biological origin has been "developed" (i.e. re-written) by Newman's own Church! The Catholic Church officially teaches that Mary was a perpetual virgin, explaining away the multiple references to Jesus' brothers and sisters in Scripture as actually being His cousins. But we can reject these silly claims as eisegesis, designed specifically to defend a weak and peculiar doctrine in the Catholic Church.
But ultimately, Jude is identified as the brother of Jesus. He is also the author of the epistle by the same name. In this epistle, he tells us "Beloved, while I was very diligent to write to you concerning our common salvation, I found it necessary to write to you exhorting you to contend earnestly for the faith which was once for all delivered to the saints." (Jude 1:3, emphasis added). Once for all. Done. Finito. The Christian faith is officially finished. We are expecting nothing new.
But this is where Catholics get particularly loopy. In an effort to defend Newman's theory, they claim that virtually all Christian traditions accept it to some degree. The most commonly cited example? You guessed it, the Trinity. This, they argue, is a developed doctrine, not found explicitly in Scripture, but rather, developed over time.
You do not have to be a Bible scholar to see the obvious flaw in this reasoning. The Trinity is one of the most easily demonstrable doctrines in the entire Bible. So easy, in fact, that the entire reason I, as a Christian, believe the doctrine of the Trinity is because it would be foolish not to. There are a great many cults in the world who do not, and they have a wide range of arguments for this rejection, but they are so clearly wrong that no one follows them without ignorance or agenda.
But in a vain effort to defend the Development of Doctrine, which is absolutely essential to explain why history does not show the Catholic Church as the one true Church established by Christ, Catholics basically suggest they have a point. To put it as one Catholic I recently debated did, the Nicene Creed "...ensures Trinitarian orthodoxy over and against individuals plausibly interpreting the Bible in line with their own heretical views."
Plausibly? What part of anti-Trinitarian heresy is plausible? In all my years as a Christian apologist, during which I have debated countless Muslims, Mormons, atheists, and of course Catholics attempting to defend the Development of Doctrine (the Trinity being the only example I've ever heard them use), along with many others, I have not once heard a compelling Biblical argument against the Trinity, nor even a slightly convincing one. As with all heresies, their arguments stem primarily from misquoting a few select verses out of context, while ignoring many others.
To really hammer home how ridiculous this is, consider that while post-resurrection heretics denied the Trinity, anti-Christian Jews had a surprisingly developed take on it, both before the Incarnation, and even right up to the medieval period. It seems, predictably, that this long-standing tradition in Judaism only began to morph into the Unitarian abomination it is today precisely because it became especially pesky to profess God as multipersonal, giving too much leeway to Christianity.
Nevertheless, the tradition can be seen quite clearly. For example, Daniel Boyarin, a non-Christian Jew, wrote, in his book "The Jewish Gospels - The Story of the Jewish Christ" wrote "The ideas of Trinity and incarnation, or certainly the germs of those ideas, were already present among Jewish believers well before Jesus came on the scene to incarnate in himself, as it were, those theological notions and take up his messianic calling."
But what we see is far more than mere "germs". In fact, there are many non-Christian Jewish sources even in the modern day that admit that older Jewish systems regarded the Messiah as Savior and Redeemer of Israel, even a God man, and that He would be King of the world. Moshe Idel even tells us, in his book "Messianic Mystics", that in the Rabbinic literature, "...the Messiah is described as one of three entities designated by the Tetragrannaton."
Now, if the Trinity is so well hidden in the oh so ambiguous Scriptures that we needed an authoritative Church to lay it out for us hundreds of years later, how is it that the Jews, whom the Catholic Church denies even their Biblically outlined authority, were able to deduce it even without acknowledging the authority of the New Testament?
The answer is obvious to anyone who isn't desperately committed to some heresy or another. The ancient Jews had a concept of the Trinity because they had the Old Testament, in which the Trinity is clearly presented in many ways. Thus, when you include the New Testament, all reasonable doubt is removed. An anti-Trinitarian heretic may well deny the Trinity in Scripture, and a desperate Catholic may say that, lacking their authority, one could reasonably do the same, but any objective reader will see the Trinity clearly taught throughout the entire Bible.
But can the same be said for, for example, the Marian dogmas? Certainly not. These are not implicitly taught doctrines that the Catholic Church simply made more clear in the later centuries. In fact, most of them are explicitly denied. You could make the case for her being the "Mother of God", depending how you mean it, since she is the mother of Jesus, and "...in Him dwells all the fullness of the Godhead bodily;" (Colossians 2:9), but her perpetual virginity is precluded by the children she bore with her husband, Joseph, who kept her a virgin until she gave birth to Christ (Matthew 1:25). Her immaculate conception is precluded by the fact Scripture affirms that all have sinned (Romans 3:23), and Mary herself rejoiced in God, her Savior (Luke 1:47). Her bodily assumption, while not specifically precluded, can, at the very least, be rejected on the basis that it isn't even mentioned until 700 years later, whereas the Bible commands us not to add to it (Deuteronomy 4:2; Proverbs 30:6), and as we saw earlier, the faith was delivered once for all to the saints in the first century.
There are a grand total of zero uniquely Catholic doctrines that are even in the same league as the doctrine of the Trinity. Thus, any and all Catholics who throw the Trinity under the bus in some futile attempt to suggest any Church, much less their own, tip their heretical hand. What they are admitting is that their faith does not match the faith delivered once for all to the saints, which we are told to earnestly contend for. And this shoddy attempt to rescue it fails as miserably as a sieve fails to hold my coffee.
Ultimately, Scripture describes itself as "...profitable for doctrine, for reproof, for correction, for instruction in righteousness, that the man of God may be complete, thoroughly equipped for every good work." (2 Timothy 3:16-17). Thus, it is not some random ink blot test. When studied diligently, one gets a fully developed picture of the Christian faith, even in the complete absence of other teachers. A man stranded on an island with nothing but a Bible will be able to read it day by day, and while starved for fellowship and accountability, will come to know Christianity fully. He will absolutely come to believe in the Trinity, albeit in different terms, but he will never draw Catholic conclusions.
Most importantly, he will have a greater understanding of the Gospel than is presented in the Catholic Church. He will not tremble in fear, believing that with no one to baptise him, he will never be free of the stain of original sin. He will not sweat blood, fearing that with no priest to consecrate his bread and wine, if indeed he may find some, he will never be able to receive eternal life by eating the real flesh and blood of Christ. He will not quiver like a coward, believing that salvation is by grace initially, but requires a host of works to maintain. No, he will see, as Scripture says, that salvation comes through faith alone, and even that to say otherwise, ironically, is damning.
This is a truth that every Catholic needs to learn very soon, as every breath draws us closer to the judgement seat of God. And there is only one mediator between God and man: Jesus Christ. The Catholic Church is a fraud, claiming His name, yet denying His word. It, like all false teachings, will perish along with its teachers. But those who confess Jesus as Lord, and believe in their heart God raised Him from the dead, will be saved, regardless of their denomination.