Biblical scholarship now operates with a few defining consensuses. Questioning the consensus can be okay. Overturning the consensus is nearly impossible. Sometimes the consensus position is solid and does not need to be overturned. There are several high-profile consensus positions, however, that are less than solid, yet questioning them is highly controversial. The consensus also differs depending on which side of the liberal/conservative spectrum one is on.
But those weak consensus positions should be questioned and overturned. Why do we love consensus so much? Consensus leads to a speculation being considered a fact which can be safely assumed as the starting point for further speculation. Think of how silly it sounds when you read books from the 1960s on the Deuteronomistic History that assume Noth's amphictyony. This was accepted as historical fact despite the lack of evidence for it. Eventually, it was abandoned.
Here's my list of the top 3 consensus positions that should be tossed out (or at least debated with an open mind to the evidence).
Top 3 Weak Consensus Positions (both secular and theological):
1. Q existed and was a source for Matthew and Luke. (Very questionable but Goodacre's fighting an uphill battle.)
2. Essenes are responsible for the Dead Sea Scrolls, and they lived at Qumran. (Admittedly, Golb's association with the alternative colors any chances of questioning this at present. However, all attempts to prove an archaeological or textual connection between Kh. Qumran and the DSS have been less than compelling. It's all speculation.)
3. The 1978 Chicago Statement on Biblical Inerrancy is the final word on the inerrancy debate. Scripture is always fully in agreement with itself. (Defending a doctrine of Scripture against Scripture itself. If the Bible says this is the Book of Isaiah, then, by Jove, that means Isaiah wrote it.)
I'm sure there are more, but these are the three that immediately came to mind. Any debate on the relative weakness (or strength if you see it that way) of these positions? Any others that I should add to the list?