While a significant number of Catholics will tell you that Martin Luther removed the Deuterocanon from the Bible because it allegedly disproved his views, the fact of the matter is the Council of Trent actually canonised the books in an attempt to counter Luther. One might say, ironically, the Catholic Church canonised the Deuterocanon in protest of the Reformation.
The Aprocypha has always been a shaky issue for the Church. The Jews considered it useful for devotional purposes, but never believed it to be inspired scripture, a view that was likewise adopted by the early Church. This was also the opinion of Jerome, who produced the Latin Vulgate. He vehemently denied that the Apocrypha was inspired canon, and did not initially include it in the Latin Vulgate. Frustratingly, I found several conflicting sources, both Catholic and non-Catholic, on exactly how they came to be in the Vulgate. Some say Jerome eventually caved to pressure and included them in a separate section, where they remained until the Reformation. Other sources say Jerome persisted in his rejection of them, and they were included in a separate section after his death. However, regardless of how the Deuterocanon came to be included in the Latin Vulgate, the fact remains that it was always of doubtful status, even within the Catholic Church, which did not officially canonise it until 1548.
It should be noted that one of Catholicism's primary arguments is that the Catholic Church must be the one true Church because without it, we would not know which books are in the canon. It is a default argument for many Catholics, to the point where, at least in my experience, they will default to it regardless of what the original topic is. Verses demonstrating Sola Scriptura? "Catholic Church produced the Bible." Verses showing that Peter wasn't a Pope? "No canon without Catholicism!" A historical overview of Catholicism's violent and bloody attempt to keep the Bible out of the hands of the laity? "You wouldn't know which books belong in the New Testament without us, so submit you filthy heathen!"
And yet, as shown in the header image, we see that the Catholic Church is so inept at recognising divine inspiration that their own sources claim they failed to complete the canon for 1500 years! Even with vicious disputes over whether or not the Deuterocanon is scripture, including from the man commissioned to produce the Latin Vulgate, as well as two Popes, they didn't attempt to officially solve the issue until people started to question their Church. What's more is that when they finally did make an official declaration, they got it wrong! The Deuterocanon isn't scripture. It's riddled with errors! It's contradictory! 1 Maccabees 9:27 even explains that it was written during a time when there were no prophets in Israel.
So, allegedly, Catholicism failed to recognise most of the inspired word of God for 300-400 years (depending on which Catholic you ask). After it did officially list most of the canon, it decided to leave the Apocrypha's canonical status open ended. It then banned the possession of the Bible at the Council of Toulouse in 1229, banned the translation and possession of the Bible at the Council of Oxford in 1408 (and then posthumously excommunicated John Wycliffe and desecrated his remains for having done just that), burned William Tyndale at the stake for the same "crime", and then finally, just as Martin Luther was stirring the pot and their power began to trickle through their fingers, they finally decided to address the issue of the Deuterocanon's status as scripture, deliberately taking the opposite view to Luther in 1548 just so they would have grounds to accuse him of heresy.
This is certainly not a Church outside of which there is no salvation. It is impossible to take a religion seriously when it does such a pathetic job of the one thing it claims to be the only Church to have successfully done. If it took 1500 years to declare the Deuterocanon as official canon, who's to say there aren't other books we should be looking for? Perhaps 3 and 4 Maccabees are scripture too? Or the Gospel of Thomas? And heck, while we're at it, why don't we start looking for the legendary Q? If the Catholic Church can just throw books in when they're in crisis, who knows what their Bible will look like in 1000 years. And heck, they made a demonstrable error, so what if one of the 66 books of the actual canon, which they claim to have given us, is a fake too? The mere fact that the Deuterocanon remained disputed for so long, only to be declared canon by Trent at a suspiciously convenient time, casts so much doubt on the Catholic Church's ability to handle scripture that even if we are generous enough to grant that they existed in the first century, and even that they produced the list of canonical books of the "Protestant" canon, we simply cannot trust them.
There are a great number of reasons to not trust the Catholic Church. The large number of unBiblical doctrines they teach. The fact that they hold, dogmatically, that only their Church has the authority to interpret the Bible. Their exceptionally violent history as opposed to the peaceful nature of the God they claim to worship. The contradictions in their various views. The whole concept of abrogation. The extreme similarity between their traditions and pagan traditions. Even the fact that they prove their religion wrong every Sunday. This religion is so ridiculous that if the Pope publicly declared that the sky was blue, I'd wonder if my eyes were faulty. But the atrocious way in which the Catholic Church handles the books of scripture should raise serious doubts about their ability to interpret those books for you.