Now, I completely agree with the materialist that, if that were true, theism would be “very unlikely” as Dawkins puts it. But that seems rather irrelevant to me. It is simply false, factually incorrect, to say that all evidence is physical–and demonstrably so.
But this is so far off the mental maps of most non-theists that it is difficult even to explain to them the concept that not all evidence is physical. They often respond with “Show it to me so that I can test it scientifically.” or “But without evidence, how can you know things?”. The point is completely missed.
But it is no less true for that. We each have a basic experience of reality: a sense of the truths of logic, a sense of one’s self as a thinking person, a sense of right and wrong, and, of course, a sense of the physical world around us. This experience is the basis for everything we know. It isn’t perfect, of course, but we accept it as valid until we have a reason to think otherwise.
When we think about it, this is the real reason why we believe what we do. No one believes in the mind because of what they saw in a brain scan (there’s no evidence for the mind to be found there, anyway). We believe in the mind because we experience our own thoughts. Nor do we believe in the moral, or even the physical, for any other reason than that we experience these things. This is almost tediously obvious.
That is, unless one has imbibed the materialist dogma that all evidence is physical. In that case, one doesn’t want to start with basic experience, but with that dogma. And this is entirely arbitrary. No one has ever been able to give a reason to believe it, and there is a rather long list of reasons why it is false.
And this is where the conversation always seems to return. I agree that we shouldn’t accept an idea without a reason to do so, but that would mean rejecting this arbitrary claim that all evidence is physical.
I’ve listed the reasons why this contradicts science, the mind, and itself, but the point for now is that it is also simply a bare assertion.