Jonathan Bernier sums things up nicely:
There is an unfortunate tendency in many circles to suppose that critical scholarship consists of pronouncing negative judgments on early Christians’ own self-understanding of their origins. I would suggest that this is a misunderstanding of what it means to be a critical historian. The critical historian is one who formulates a question, attends to the data relevant to answering that question, weighs possible answers, and then affirms that answer which handles the relevant data best. Sometimes that will much resemble early Christians’ self-understanding of their own origins; sometimes it will be remarkably at variance therewith. The skeptic supposes programmatically that the best answer will be at variance with traditional narratives. That is bias, the bias known as skepticism, which takes as its sinister twin the bias known as credulity: the programmatic supposition that the best answer will be fully congruent with traditional narratives. Both arbitrarily close off possible answers before the investigation even begins. As such, the spirit of critical thought is programmatically opposed to both.