Person 1: "I believe X."
Fallacy dude: "Well, that is indeed an option, but no one could seriously believe that."
Example captured in the wild: "So you seem to be suggesting that St. Peters Basillica and the Taj Mahal are the result of natural processes alone. In my original post I suggested that this was indeed an option for the naturalist although what I intended to point out is that it is too absurd to take seriously and thus we have a defeater for naturalistic belief."
Call me crazy, but it's quite true that I believe no supernatural processes were involved in building the Taj Mahal.
(Just to be clear, in the discussion so far, this person himself recognizes that a naturalist may regard mental processes as equivalent to or supervening on physical processes, and are thus natural processes. So it's not that the naturalist is claiming that the Taj Mahal was built by the wind or something.)