One can’t believe that God said X to those he loves and that X is false, and in this sense it is absurd to talk about what could falsify faith or to think that a believer is naive or engaged in special pleading for lacking falsification criteria.*
Arguendo, all our beliefs might be mistaken, but it does not follow that all can have falsification criteria, only that, say, what falsifies our belief in X is impossible to specify before we find ourselves calling it false. I may go from believing the gods tell me to cut out the hearts of my enemies to believing God tells me to love my enemies, but this does not make it logical in either case for me to specify falsification criteria. I can only have a general openness to truth and see what I find. I cannot be open to changing my opinion but it’s contrary to experience to say I only ever do things that I was previously open to doing.
Here’s my basic point, which I think is given from both reason and experience: Just because you might get a good reason for changing your mind does not mean you could have had that reason in advance, even as a vague sketch or outline. And so one can recognize that he might be wrong about anything he believes and still insist that it is impossible for him to give any criteria that might refute his belief in the divine word, or that he is even open to the possibility.
*Look, “falsification” only survives in the shallower end of pop scientism. The idea is dead among most philosophers of science and many Naturalists. That said, it’s important to note that “falsification” means not just identifying something that would refute your belief but also treating it as a possibility that you can’t dismiss a priori. And so even though falsification criteria have been largely abandoned, a more restricted view of falsification that ruled out exactly what faith wants to do with experience might still seem rational. So briefly, we can distinguish
a.) Popperian, traditional falsificationism: P is scientific iff it is falsifiable. (This idea has been abandoned.)
b.) Weak falsification: It cannot be rational to rule out some historical or physical facts a priori. (Faith claims to do even this on the basis of divine testimony while no other discourse claims to do so.)