[quote="jamil_joseph02, post:9, topic:286877"]
Well, I've asked this because I've heard some Protestants disagree that the Catholic church was the one Christ founded. I've also heard some make a claim that Constantine was responsible for the "introduction of paganism" in Christianity.
So if the Catholic Church with which Luther was protesting to is not the true Church, then what happened to that Church Christ founded and how did the Catholic church "overcame" it?
What are your reasons for agreeing or not agreeing with these claims?
But if you agree that Jesus founded the Catholic Church, then I wonder, why not be Catholic at all?
A statement like "the Catholic Church is the one Christ founded" is not as simple as it sounds.
What Catholics mean by it is something like "there is a divine essence to the Church, imparted to it by Christ, which has uniquely persisted within those Christian communities who are in union with the successor of St. Peter and not, at least in the same way, in other communities." If one believes this, then one should be Catholic. (I more or less believe this, or at least find it highly persuasive, so I probably should be Catholic:o.)
On the other hand, one could also mean something like "the religious body identified by its union with the Pope and calling itself the Catholic Church is identical in every respect, essential or accidental, with the community founded by Jesus." That claim is obviously false. No one who thinks it through believes it.
In between these two claims is the obvious fact that four Christian communions presently in existence (the "Catholic Church," the "Orthodox Church," the "Oriental Orthodox churches," and the "Church of the East") have a kind and degree of continuity with early "Catholic" Christianity that other churches do not have (including even Anglicanism, which can probably make the best claim of the other Christian communities).
And then, of course, we have the question of how the early Catholic Church (from which these four "apostolic" communions derive) related to other early groups calling themselves Christian, none of which have survived to this day.
As you note, some folks (fundamentalists and Mormons, mostly) believe that the early Church apostasized at some point, and either was eventually restored (the Mormon view, held by some more orthodox groups as well in some form or another) or somehow persisted in an underground and/or spiritual, individualized form.
A second, more nuanced view, held mostly by conservative Reformed or Lutheran Protestants, is that the original Church slowly became more corrupt, until, in a state of serious corruption, it was reformed by the early Protestants. Those Catholics who rejected these reforms and embraced the teachings of the Council of Trent would then be apostates, leaving Protestants as the true "Catholics" (and what of the Eastern churches? answers vary.). This is probably the view that best represents the teachings of the original Reformers, though they weren't entirely consistent.
Most modern Protestants, however, don't believe either of these things. They believe that all churches that hold to basic Christian beliefs (most commonly identified with the Apostles' Creed) are continuations of the Church Christ founded, and that none of these churches is perfect or infallible. So one can say that the Catholic Church is in continuity with the Church Christ founded in its essentials, without saying that one should become Catholic--because there's no reason to abandon whatever other church one belongs to, which is also in continuity with the original Church, and may have "purer" doctrine or better practices in one way or another.
This last view isn't as completely contrary to the Catholic view as the polemic one hears on this forum would have one believe. Vatican II's language of imperfect participation, the Church as the pilgrim people of God, etc., leaves a good deal of room for something like this third, ecumenical view. The bottom line, however, is that the Catholic Church claims to be infallible in its central doctrinal/moral tenets and basic liturgical practices, and furthermore claims that all Christians (once rightly informed) are obligated to seek union with the bishop of Rome.