I was reading a blog the other week, and I can't remember exactly where it was, but it was arguing against using the phrase "Biblical Christian." It was briefly stated that this was a sort of redundant phrase like "true truth." You aren't really saying anything or adding anything. The argument was drop it and just say "Christian" or say "truth."
If I recall, the blog was by some sort of theologically liberal/progressive or even emergent/post-emergent, or what ever the buzz words now are.
Here's the problem, in most cases saying "Biblical Christian" would be redundant and indeed it should be. Saying that "the truth is true" should be redundant or the even arguing for that the Bible is true and inerrant is equally repetitive.
Sometimes I wish this repetition was unnecessary. However, I would argue that there are times that this repetition is needed and helpful because other people have come along and moved the goal posts. Someone starts defining a Christian along cultural terms or other terms besides commitment to the Bible. Now I agree that going to far and they have used the word "Christian" in a wrong way. However, most times they keep the label and argue for their place in the big tent. So the term "Biblical Christian" is then added by those who have not moved to clarify their position over against those who have added something to the term Christian.
It's a helpful move and its actually an attempt to keep things simple--even if prior to the rise of a new movement/idea the clarification is unnecessary.
The rise of the term "inerrancy" can be charted along similar lines. It was fine to say "infallible" and "true" but then people started using those terms in a way that added meaning to the idea. So "infallible" for some became "true on spiritual matters, but potentially false/misleading on historical issues." People claimed that "the Bible is true" but then caveated it was "true in a certain way." Thus "inerrant truth" was a clarification that indeed it really is true in all things since truth has no error.
Even "true truth" functions similarly. When the notion of "truth" became associated with subjectivism and certain postmodern theories, the phrase "true truth" can be used as a layman's term for a correspondence theory of truth that say "truth corresponds to the way thing actually are in reality (not some spiritual or reader response notion that might not comport to 'the way things actually are.'" It was an attempt to say the truth is not less than objective (although it may entail more than that).
So my contrarian thought is that its nice to quip that we shouldn't add phrases like "Biblical" to "Christian" or even say "Biblical isn't a word in the Bible." Or we should stick to "Christian" and "truth" without additives. That would be a nice sentiment if we weren't forced by false teachers and opponents to Biblical doctrine to modify language in defense of the truth in order to defend concepts and Biblical doctrines that have been handed down to the saints once for all in the Bible.
Church history, to some degree, has always responded this way. It would be nice if everybody at Nicea could have just said "Jesus is God" but because people were adding an * and saying *but not God in the way the Father was God, the term homoousia became a good and necessary clarification to remain faithful to Biblical doctrine found in Scripture.