Protestant epistemology has lead to the creation of thousands upon thousands of divided Protestant sects that cannot come together and agree on a single point of doctrine. What is the source of that Protestant doctrinal chaos if it is not the doctrine of sola scriptura? Does the Baptist man I mentioned really believe anything different than the tens of millions of Protestants that also claim to believe that the Protestant Bible is the ONLY source of infallible authority for a Christian?(source)
Did you notice something interesting? The claim is that all these "sects" (meaning denominations) cannot agree "on a single point of doctrine." But then we are essentially given two points of alleged agreement:
1) The Protestant Canon
2) Sola Scriptura
We could probably add other things as well, such as theism and a rejection of the fictions of the papacy and purgatory. In fact, there are a huge number of beliefs that are characteristic of virtually all (if not absolutely all) of this mass of supposedly dis-unified brethren.
The critic wants to have it both ways: he wants to claim that this huge mass of denominations can't agree on anything, and that they do agree on a couple things that the critic himself rejects. It's really not a fair criticism, but it is remarkable in how blatantly unfair it is!