Hullo, Alex. Welcome to the forums. And I congratulate you on your curiosity.
Yes, Catholics are Christians. We are supposed to love the Word of God, and to have a personal relationship with Jesus Christ. However, we are very different from the vast majority of Protestantism on many important aspects.
One important difference is that Protestants do not accept Christian history - which the Catholic Church calls “Sacred Tradition” - as having the same authority as Scripture. For Catholics, not only is the Bible important, but the things Christians taught after the Bible was written are also important because, we assume, Christ gave us one way to follow Him - one Truth. Granted, that truth is found in the Bible. But it is found in interpretations of the Bible. The Bible, like any book, has to be interpreted.
Case in point, our second major difference with most Protestants: the body and blood of Jesus on the altar. We read John 6 and Matthew, Mark, and Luke, as well as 1 Corinthians 11, and take Christ very, very literally when he says “This is My body and this is My blood” at the Last Supper. We believe that, in context, Christ can mean nothing less than that bread is now His flesh, and that wine is now His blood. I’m going to guess that you are with the majority of non-Catholic Christians, and believe either that the bread and grape-juice possesses either a spiritual presence of Jesus, or is completely and only symbolic.
We differ so very widely on this issue because we interpret the Bible in different ways, and it has real consequences. Which leads me to the third difference: we believe Christ is really present in the bread and wine - that is, His flesh and blood really, physically are where once there was a white wafer and grape wine. We worship His flesh and blood and treat it with the utmost respect. Most Protestants have no such respect for their bread and grape juice, and feel free not to reverence it.
Now this leads to a fourth difference I should like to point out, and probably one good reason a Catholic would want only to marry a Catholic. The first three differences are, usually, so. Therefore, the typical Protestant must conclude that the Catholic is engaging in a form of idolatry, albeit accidentally, for he is giving glory to bread and wine what is due only to God. The Catholic, on the other hand, must conclude the Protestant is being, again accidentally, disobedient to Our Lord’s and to St. Paul’s commands, and the Protestant is deprived of a very important spiritual grace.
This leads me to my final difference I will note. Why and how could a Catholic and Protestant come to such shockingly contradictory conclusions? The answer is simple: the Protestant is using the Bible, isolated from history and the context of what it is saying, to make interpretations. The Catholic uses the Bible, in conjunction with history and its historical context within history, to draw conclusions. As Blessed Henry Cardinal Newman once said, “To be deep in history is to cease to be Protestant.” Thus the Catholic has only one set of dogmas, while Protestants, sadly, have divers contradictory sets of dogmas all drawn from the same book, isolated from its context, so that it might mean any number of things. That is why there are Anabaptists, Baptists, High Church Anglicans, Low Church Anglicans, Lutherans, Calvinists, Reformed Baptists, Southern Baptists, non-denominationals, post-denominationals, postmillenials, Seventh-Day Adventists, nontrinitarians, evangelicals, evangelical reformeds, Methodists, Quakers, Shakers, and dozens upon dozens of other types of Protestants all originating from the same understanding of the Bible: sola scriptura.
Now you might say, “But I don’t believe all these different churches to be what I believe.” True. Very true. But you all use practically the same method and materials to derive these contradictory beliefs, do you not? What is different in form between the way a Baptist and the way a non-denominational interpret Scripture? Not much, except the results. :shrug:
My point, then, basically is not to incriminate you particularly, but to point out that, frankly, all Protestants truly do interpret the Bible through the lens of sola scriptura - the Bible alone and isolated from anything or anyone but the interpreter - and this is a vital, almost incompatible difference between Catholics and Protestants.