I recall reading about a Catholic bishop who visited a mosque saying that he felt right at home there with his "fellow fundamentalists." Can you imagine a Protestant being referred to by any Catholic as a "fellow fundamentalist?"
I was doing some reading about Armenia yesterday, and I read that the Armenian Church is rabidly opposed to "sects" that threaten Armenian "national identity," but have no problem with people who practice a reconstructed Armenian paganism . . . because reconstructed Armenian paganism, like Armenian chrstianity, helps bolster Armenian "national identity!!!"
There is absolutely no doubt that the ancient liturgical churches are more authentic than any Protestant "restoration" based on "the bible" . . . but there is also absolutely no doubt that those ancient churches are sick and twisted beyond measure.
(2) Self-described fundamentalist congregations are not in the habit of inviting Catholic or Orthodox prelates to their churches and frankly, do not like to even address the prelates by their titles.
(3) Interaction between fundamentalist Protestant pastors and Catholic and Orthodox clergy usually take place in venues like meetings in support of marriage or life rather than churches.
(4) American Protestants are highly focused on condemning religious law largely because their tradition comes from the "Dissenters" of England, Holland and Germany who opposed not just Catholicism and Orthodoxy but also the official Reformed, Anglican and Lutheran state churches of Europe.