I have been asked for evidence for the existence of the God of the Bible, Who alone is God and Creator. My favorite three lines of argumentation are the Cosmological (aka Kalam) argument, the Resurrection of Jesus Christ in real space and time, and the Transcendental argument. Perhaps the former 2 I might deal w/ later, but the latter gets to the heart of the issue when an atheist questions God's very existence.
Strangely relevant to my discussion w/ the Jolly Nihilist is the famous Bahnsen-Stein debate from several years ago. I say "strangely relevant" b/c it seems to me that the JN takes virtually the same position as Stein in the debate, and so Bahnsen's points strike directly at the heart of the JN's position.
Below I have pasted the relevant portion from Greg Bahnsen's opening statement. The unfairly short answer to "How do you know God exists?" is "The impossibility of the contrary." I expect to refer back to this post a few times in the future.
In your mind, just replace every occurrence relevant to "Dr. Stein" (Bahnsen's opponent in the debate) w/ a more general wording, and you'll get the idea.
The assumption that all existence claims are questions about matters of fact, the assumption that all of these are answered in the very same way is not only over simplified and misleading, it is simply mistaken. The existence, factuality or reality of different kinds of things is not established or disconfirmed in the same way in every case.
We might ask , "Is there a box of crackers in the pantry?" And we know how we would go about answering that question. But that is a far, far cry from the way we go about answering questions determining the reality of say, barometric pressure, quasars, gravitational attraction, elasticity, radio activity, natural laws, names, grammar, numbers, the university itself that you're now at, past events, categories, future contingencies, laws of thought, political obligations, individual identity over time, causation, memories, dreams, or even love or beauty. In such cases, one does not do anything like walk to the pantry and look inside for the crackers. There are thousands of existence or factual questions, and they are not at all answered in the same way in each case.
Just think of the differences in argumentation and the types of evidences used by biologists, grammarians, physicists, mathematicians, lawyers, magicians, mechanics, merchants, and artists. It should be obvious from this that the types of evidence one looks for in existence or factual claims will be determined by the field of discussion and especially by the metaphysical nature of the entity mentioned in the claim under question. Dr. Stein's remark that the question of the existence of God is answered in the same way as any other factual question, mistakenly reduces the theistic question to the same level as the box of crackers in the pantry, which we will hereafter call the crackers in the pantry fallacy.
I take it he wishes to judge hypotheses in the common sense - by tests of logical coherence and empirical observation. The problem arises when Dr. Stein elsewhere insists that every claim that someone makes must be treated as a hypothesis which must be tested by such evidence before accepting it. "There is to be nothing," he says, "which smacks of begging the question or circular reasoning." This, I think, is oversimplified thinking and again misleading, what we might call the Pretended Neutrality fallacy. One can see this by considering the following quotation from Dr. Stein: "The use of logic or reason is the only valid way to examine the truth or falsity of any statement which claims to be factual." One must eventually ask Dr. Stein, then, how he proves this statement itself. That is, how does he prove that logic or reason is the only way to prove factual statements? If by logic or reason, then he is engaging in circular reasoning; and he's begging the question which he [supposedly] forbids. If he says that the statement is proven in some other fashion, then he refutes the statement itself, that logic or reason is the only way to prove things.
Now my point is not to fault Dr. Stein's commitment to logic or reason, but to observe that it actually has the nature of a pre commitment or a presupposition. It is not something that he has proven by empirical experience or logic, but it is rather that by which he proceeds to prove everything else. He is not presuppositionally neutral in his approach to factual questions and disputes. He does not avoid begging crucial questions, rather than proving them in what we might call the garden variety, ordinary way. Now this tendency to beg crucial questions is openly exposed by Dr. Stein when the issue becomes the existence of God; because he demands that the theist present him with the evidence for the existence of God. Well, theists like myself would gladly and readily do so. There is the evidence of the created order itself testifying to the wisdom. power, plan, and glory of God. One should not miss the testimony of the solar system, the persuasion of the sea, the amazing intricacies of the human body. There's the evidence of history: God's deliverance of His people, the miracles on Passover night and [at] the Red Sea, the visions in Isaiah, the Shekinah Glory that filled the Temple, the Virgin Birth of Jesus, His mighty miracles, His resurrection from the dead.
There's the evidence of Special Revelation, the wonder of the Bible as God's Word, unsurpassed in its coherence over time, in its historical accuracy and its life-renewing power. In short, there is no shortage of empirical indicators or evidences of God's existence - from the thousand stars of the heavens to the 500 witnesses of Christ's resurrection. But, Dr. Stein precludes the very possibility of any of this empirical evidence counting as proof for God's existence. He writes, " Supernatural explanations are not allowed in science. The theist is hard put to document his claims for the existence of the supernatural if he is in effect forbidden from evoking the supernatural as a part of his explanation. Of course, this is entirely fair; as it would be begging the question to use what has to be proved as a part of the explanation." In advance, you see, Dr. Stein is committed to disallowing any theistic interpretation of nature, history or experience. What he seems to overlook is that this is just as much begging the question on his own part as it is on the part of the theist. who appeal to such evidence. He has not at all proven by empirical observation and logic his pre commitment to Naturalism. He has assumed it in advance, accepting and rejecting all further factual claims in terms of that controlling and unproved assumption. Now the theist does the very same thing, don't get me wrong. When certain empirical evidences are put forth as likely disproving the existence of God, the theist regiments his commitments in terms of his presuppositions, as well. Just as the Naturalist would insist that Christ could not have risen from the dead, or that there is a natural explanation yet to be found of how he did rise from the dead, so the supernaturalist will insist that the alleged discrepancies in the Bible have an explanation - some yet to be found, perhaps - and that the evil of this world has a sufficient reason behind it, known at least to God. They both have their governing presuppositions by which the facts of experience are interpreted, even as all philosophical systems, all world views do. At the most fundamental level of everyone's thinking and beliefs there are primary convictions about reality, man, the world, knowledge, truth, behavior, and such things. Convictions about which all other experience is organized, interpreted, and applied. Dr. Stein has such presuppositions, so do I, and so do all of you. And it is these presuppositions which determine what we accept by ordinary reasoning and evidence, for they are assumed in all of our reasoning - even about reasoning itself.
How should the difference of opinion between the atheist and the theist be rationally resolved? That was my opening question. We've seen two of Dr. Stein's errors regarding it: the crackers in the pantry fallacy and the pretended neutrality fallacy. In the process of discussing them we've observed that belief in the existence of God is not tested in any ordinary way like other factual claims. And the reason for that is metaphysically because of the non-natural character of God, and epistemologically, because of the presuppositional character of commitment for or against His existence. Arguments over conflicting presuppositions between world views, therefore, must be resolved somewhat differently, and yet still rationally, from conflicts over factual existence claims within a world view or system of thought. When we go to look at the different world views that atheists and theists have, I suggest we can prove the existence of God from the impossibility of the contrary. The transcendental proof for God's existence is that without Him it is impossible to prove anything. The atheist world view is irrational and cannot consistently provide the preconditions of intelligible experience, science, logic, or morality. The atheist world view cannot allow for laws of logic, the uniformity of nature, the ability for the mind to understand the world, and moral absolutes. In that sense the atheist world view cannot account for our debate tonight.