It is a standard evangelical complaint is that critics treat the Bible with a degree and type of skepticism that they do not employ under similar circumstances with other texts. I attributed this view to Lewis, but I did not actually make the argument myself.
The complaint Lewis made about texts was that biblical scholars made judgments about texts which conflicted with what he knew as a literary scholar. Some biblical scholar had described John's gospel as a spiritual romance along the lines of Pilgrim's Progress, and Lewis thought that someone who said something like that had had his nose in biblical texts for so long that he was unfamiliar with what romances are really like.
The impression that I have is that radical Biblical scholarship is forced to accept certain interpretations of texts in order to avoid accepting the supernatural content that you would have to accept on interpretations that would come more naturally otherwise.
However, by itself this is not a crime. Everyone evaluates situations based on what they take to be antecedently probable. Different scholars approach biblical texts with different credence functions. No one comes in from a neutral perspective, and we have no reason to expect that they should. However the fact that Bultmann has massive expertise in the study of the NT documents is going to cut a lot less ice with me than it would otherwise if I know that he rules out the possibility of the miraculous from the outset. Which he does (and offers appallingly bad arguments for doing so). What gets tricky is sometimes the expertise of someone like Bultmann will convince students that he has reached his skeptical conclusions based on the evidence, when in fact he has reached his skeptical conclusions by presupposing them to begin with.