The Catholic Church along with the Orthodox Church, to a slightly lesser extent, have been the Churches that have followed the Gospel truths and teachings the closest since the very beginning of Christianity as established by Jesus Christ. These were the basis for Christianity for over 1500 years. In the early 16th century Martin Luther went on a rampage and nailed his 95 thesis to the cathedral door. While he did have a few legitimate complaints that were later addressed at the Council of Trent, much of what he posted in his letter was pure heresy and went totally against some very basic tenets of Christianity as it had been taught for 15 centuries and had been handed down by Christ to his apostles. Luther rewrote the Bible and tossed out some books that did not agree with his own personal beliefs. Where he could not toss a book, he slightly altered the scripture wording so that its meaning often took on the opposite view from the original intent. Some parts of the Bible he left intact but chose to ignore them or stated that the verses should not be taken literally.
So to put the answer briefly, it was Martin Luther who began the Protestant Revolt in the 16th century that took some opposite views from long established truths of the Catholic Church as establish by Jesus Christ. No other church can claim to be the reservoir of true Christianity although all originally had their roots in Catholicism. These relative new-comers have so distorted and watered down the original meanings of the scriptures so as to make them, at times, totally 180 degrees at odds with the original intent.
The question is posted in the Catholicism category and the answer is a Catholic answer. If you do not like to hear the truth from a Catholic point of view, then post your question in the Protestant category.
The leaders of the Catholic Church believe it obtains its legitimacy from being the Church set up by Jesus Christ himself. As the Orthodox Churches could equally make the same claim, the Catholic Church claims further legitimacy from its inheritance of the role of Saint Peter, supposedly the first bishop of Rome.
Catholics are not permitted to challenge these claims, although there are good reasons to doubt them. In the end, it is open to Christians to worship as they see fit, regardless of which denomination they may been brought up in.