My wife and I are two such Christians... we are modified (heavily) by other teachings, including Pagan and Buddhist ideas, including the idea of finding "contentment" as opposed to "happiness" (given as emotional states are fickle and apt to change on a whim). However, at our core, we are Christian.
Granted, we also believe that most major religions are/could be the very same teachings/people, but with different labels and recorded from different viewpoints. Case in point - what's to say Yahweh, Jehova, Allah, etc aren't the same entity, but appearing in differing forms to different people?
Admittedly this is off-topic now, but you raise an interesting point about the definition of being a christian (or any other religion). To what extent can you ignore some of the core teachings but still define yourself in that way? Is this how the different sects formed, with people rejecting some teachings in favour of new interpretations? Take islam: I saw a chart which showed something like 20 different sects, I couldn't name them all, but you have sunni, shia, and the one Assad belongs to (allawites?) and a lot more.
As far as the different religions all being the same basically, their teachings are quite different, no? I don't think that works. (But I'm no expert, so correct me if I'm wrong).