I recently encountered a discussion between an atheist and a Christian that went something like this:
A: How do you know that Jesus did miracles and created the universe? Using your own reason, and without using the Bible, prove to me he did these things.
C: Jesus was God, and as such, could do miracles.
A: You are giving your opinion. I asked how you know? If you cannot prove it, you are basing beliefs on your unfounded personal opinion, certainly not evidence.
Such a discussion is likely common in atheist circles. The atheist reasoning has more than one significant flaw.
First, there is no good reason to eliminate the Bible from a historical discussion, especially one about its main subject. Since external sources have proven the Bible accurate in a wide variety of historical instances, we can therefore trust it in the areas that it is the primary source.
Second, in this discussion the atheists assumes the high ground and asks Christians to prove the creation of the universe, but the atheist has no more ability to explain the beginning of the universe than the Christian. The atheist accuses the Christian of something he is guilty of himself, namely belief without empirical evidence. The atheist berates the Christian for something which he has no better answer. In fact, the atheist answer would seem to ultimately assume that the effect of the universe resulted without a cause, an absurdity.
Third, the question asks for both knowledge and proof, two very different areas of philosophy. If we are to dive into the depths of epistemology, especially post Gettier, we end up with questions about how to prove knowledge of anything, not just religious history. Therefore the knowledge question is at best not confined to religious knowledge.
Fourth, knowledge of any historical event proves difficult to the stringent philosopher that demands empirical proof. Using such a high epistemological standard, we cannot prove that we were not created five minutes ago with the false knowledge of our childhood. Such strict standards of doubting historical evidences leaves us with no way to prove we know anything in history, a standard no one takes seriously, but only applies when they want to dismiss views with which they disagree.
Fifth, as Alvin Plantinga points out, there are many things everyone holds to be true that we cannot prove empirically. We cannot prove what we had for breakfast this morning or that we are feeling frustrated, but we do not doubt these things as true. So the suggestion that if we cannot give empirical evidences then we have no basis for knowledge, therefore we are unreasonable, is a claim that is itself irrational and unfounded.
Lastly, it is much easier to toss out these persuasive hand grenades than it is to explain how irrational they are. It has taken me all these words to explain the hollowness of the accusation, while it only takes a brief comment to make the accusation. To borrow Hume’s phrase, the current atheist resurgence is based more on sophistry and illusion than on objective reason and evidence. Such statements demonstrate the adept persuasion techniques of modern atheists, but also demonstrates their irrationality.