A reader inquires, "I'm curious, if someone asked you what you were more certain of, your hands or belief in the existence of God, how would you respond?"
The first thing a philosopher does when asked a question is examine the question. (Would that ordinary folk, including TV pundits, would do likewise before launching into gaseous answers to ill-formed questions.) Now what exactly am I being asked? The question is ambiguous as between:
Q1. Are you more certain of the existence of your hand or of the existence of God?
Q2. Are you more certain of the existence of your hand or of your belief in the existence of God?
My reader probably intends (Q1). If (Q1) is the question, then the answer is that I am more certain of the existence of my hands than of the existence of God. My hands are given in sense perception throughout the day, every day. Here is one, and here is the other (he said with a sidelong glance in the direction of G. E. Moore). It is not perfectly certain that I have hands, or even that I have a body -- can I prove that I am not a brain in a vat? -- but it is practically certain, certain for all practical purposes.
By the way, it borders on a bad joke to think that one can prove the external world by waving one's hands around as Moore famously did. Still, if I don't know basic facts such as these 'handy' facts, then I know very little, things of the order of 'I now seem to see a hand' but not 'I now see a hand.' (I am using 'see' as a verb of success: If S sees an F, there there exists an x such that x is F and S sees x.)
So, for practical purposes, I am certain that my hands exist. But I am not certain in the same sense and to the same degree that God exists. The evidence is a lot slimmer. This is not to say that there is no evidence. There is plenty of evidence, it is just that it is not compelling. There is the evidence of conscience, of mystical and religious experience, the consensus gentium; there is the 'evidence' of the dozens and dozens of arguments for the existence of God, there is the testimony of prophets. But none of this evidence, even taking the whole lot of it together, gets the length of the evidence of my hands that I get from seeing them, touching them, clapping them, manipulating things with them.
When I fall down and feel my hands slam into the hard hot rock of a desert canyon, then I know beyond any practical doubt that hands exist and rock exists. Then I say with 'Cactus Ed' Abbey, "I believe in rock and sun." In that vulnerable moment, alone in a desolate desert canyon, it is very easy to doubt that there is any providential order, that there is any ultimate intelligibility, that there is any Sense beyond the flimsy and fragmented sense we make of things. But it is practically impossible to doubt hands and rock and sun.
The difference could be put like this. The existence and the nonexistence of God are both of them epistemic possibilities: for all I can claim to know, there is no God; but also: there is a God. Both states of affairs are consistent with what I can claim to know. But it is not an epistemic possibility that these hands of mine do not exist unless one takes knowledge to require an objective certainty impervious to hyperbolic doubt.
In the case of my hands there is really no counter evidence to their existence apart from Cartesian hyperbolic doubt. But in the case of God, not only is the evidence spotty and inconclusive, but there is also counter evidence, the main piece of which is the existence of evil. It is worth noting, however, that if one would be skeptical, one ought to doubt also the existence of evil, and with it, arguments to the nonexistence of God from the putative fact of evil. How do you know there is evil? No doubt there is pain, excruciating pain. But is pain evil? Maybe pain is just a sensation that an organism feeling it doesn't like, and the organism's not liking it is just an attitude of that organism, so that in reality there is no good or evil. Pain is given. But is evil given? Pain is undeniable. But one can easily deny the existence of evil. Perhaps the all is just a totality of value-indifferent facts.
As for (Q2), it makes reference to my belief in God. Whether you take the belief as a disposition or as an occurrent state, the belief as a feature of my mental life must be distinguished from its truth-value. I am not certain of the truth of my belief that God exists, but I am certain of the existence of my belief (my believing) that God exists. As certain as I am that I have hands? More certain. I can doubt that I have hands in the usual Cartesian way. But how can I doubt that fact that I have a belief if in fact I have it?