Where does the idea that Catholics are the only ones going to be saved come from? Mormons have a similar point of view as well as many other religions.

Details: I was talking to a Catholic (God so help me!) and he stated this, "There is no salvation outside the one true Church, the Catholic Church". Where do crazy ideas like this come from? And how is it refuted in scripture?

You and I may refer to Catholics, Jehovah Witnesses and Mormons as cults. But it is meaningless to say they're part of a cult as they have already been deceived as accepting something that is false (having no biblical basis) as truth.

I can refute this in Romans 10:9 as a Christian may be a Baptist or a person may be a Christian with no religious affiliation. But, please add to this...