Well, for the TRUEST faith to and within most religions, a love of all humanity as God incarnate is paramount. Thus, to "hate" another religion or s/he who practices it is rather hypocritical.
There are some religions that lack this "love thy neighbor as thyself/ what you do to the least of you, you do to Me (God)" and instead, usually through a geographic or nationalistic dominance (or domination!), preach an extreme loyalty to "the one true God/Allah/whoever" - extreme as in to the point of mortal sacrifice and/or war. "Jihad".
Thus, I don't think it is out of devotion (or at least informed devotion) to one's denomination or "God" that such exclusivity and condemnation of "the other" exists.
I believe it is out of a *learned* and (okay, perhaps indoctrination is too strong a word) acculturated adopting and/or adapting to the norms of the religion you happen to practice. The more comfortable with and convinced of the idea that YOUR religion "has it right", the more comfortable you are with shunning, condemning or even hating other religions.
Perhaps I should have said acCULTurated.