What are the Characteristics of a NT Christian?

[RoadRunner79]

Why is that (not believing gives him more credibility)?  Is this a principle, that can be applied elsewhere?

For me, it depends on the reasons, not the position.  I may even agree with someones conclusions, but not with their reasons or method, I don't think that makes them more credible.

To me it depends on the reasoning.  If you're a believer, you're emotionally involved and invested.

It seems to me a number of atheist get quite emotional and seem fairly invested (despite claims of only skepticism).  Can I just dismiss everything they say as biased?
I can understand this position perhaps on an individual basis (if given reason to do so), but it doesn't seem right to assume it; on a general level.

Perhaps this is your bias showing?

Regarding Bart Ehrman, his work differs quite a bit, between his popular writings and talks, to his more scholarly work. For example here is what Ehrman say's in an interview found in the appendix of some versions of "Misquoting Jesus" (my understanding is that this is removed from later additions).

Bruce Metzger is one of the great scholars of modern times, and I dedicated the book to him because he was both my inspiration for going into textual criticism and the person who trained me in the field. I have nothing but respect and admiration for him. And even though we may disagree on important religious questions – he is a firmly committed Christian and I am not – we are in complete agreement on a number of very important historical and textual questions. If he and I were put in a room and asked to hammer out a consensus statement on what we think the original text of the New Testament probably looked like, there would be very few points of disagreement – maybe one or two dozen places out of many thousands. The position I argue for in ‘Misquoting Jesus’ does not actually stand at odds with Prof. Metzger’s position that the essential Christian beliefs are not affected by textual variants in the manuscript tradition of the New Testament.

Frankly, I find most of the people that you here speak on a given topic be it religion, atheist, evolution, or Dr. Ehrman, are fairly involved and invested.