In the Wanderer post below, Paul Likoudis brings up the subject of "Americanism," which is actually a group of related heresies. The article specifically mentions the tendency of Americanists to downplay the Church's teaching that outside the Church there is no salvation.
Recently I was in a combox conversation with some people (not Catholics) who were trying to claim that the Church in the modern age has drastically altered this teaching, that it is no longer in force (and that thus the Church could any day change her teaching on birth control, which is a non-sequitur anyway). Their insistence seemed to hinge on two things, neither of which were true: one, that the Universal Church always and everywhere taught that anyone who wasn't baptized a Catholic was definitely going to spend eternity in Hell, and two, that the Second Vatican Council changed this by saying that anybody could get to Heaven provided they were nice and did good deeds.
It's pretty difficult, within the scope of a comment box argument, to point out the many places where both of these ideas are wrong; but it's even more difficult to explain that the Church does indeed still teach that outside the Church, apart from her sacraments and presence, there is no salvation--there are not "many paths" to the truth, but one path, though other paths may at times be leading toward some part of the truth. This is why the Church teaches that the fullness of the means of salvation is present in the Catholic Church, which is indeed necessary for man's salvation.
The degree to which this misunderstanding of what the Church has always taught, and still teaches, about "outside the Church there is no salvation" is exacerbated by lingering Americanism which still impacts the Church here in America today can't really be known. I'm fairly sure, though, that it plays a role--that the understandable and even laudable desire Catholics in America have to get along with our Protestant and non-Christian neighbors led unfortunately to a distortion, sometimes deliberate, in what the Church teaches about her necessary role for the salvation of all men. It is important for the Church here in America to continue to teach this clearly, without such misunderstandings.