I know that 2 + 2 = 4. I don’t know this inductively because I have examined all possible answers to the question ‘what is 2 + 2?’. I know it deductively through other methods. As such, I don’t need to have examined all possible answers to the question (thankfully, since there are an infinite number of possible answers). If someone told me that 2 + 2 = 5, I know that they are wrong. I’ll examine their reasoning to help show that they are wrong, and why they are wrong.

Now, if someone came up to me with a twenty page paper, with hundreds of equations, big long explanations and proofs, and at the end it appeared that they have proved 2 + 2 = 17, well, I know that they are wrong. Even if I go through the paper quickly and don’t identify right away where they went wrong, I know that they are wrong, because I know that 2 + 2 = 4. And I know that for reasons other than the need to disprove their apparent proof here in this paper. So I can happily stand on the truth of my position while I try to determine where their proof falls apart. Maybe they divided by zero in some complex, easy to miss equation. Maybe they made a logic error. It could be all sorts of things. So I’ll go through it and try to see where it fails, all the while knowing that I am correct about 2 + 2 = 4, because my knowledge of that doesn’t rely upon disproving this person’s apparent proof that 2 + 2 = 17.

It’s similar with Christianity. I know that Christianity is true via divine revelation. My knowledge of this isn’t based upon inductively proving other worldviews false. It’s based upon the revelation of God which He has made evident to me in such a way that I can know it, and can’t be wrong about it.

So when discussing the issue with someone else, and critiquing their worldview, I can stand completely firm on the knowledge of the truth while I examine the ways the other person’s worldview falls apart. Some are simple, like atheism or deism – they essentially refute themselves before getting out of the starting gate. Others may be quite complex and difficult – Judaism and Roman Catholicism both have many aspects of the truth in them, and therefore it’s more difficult to peel back the layers and show people where their position falls short or breaks down. But ultimately, all non-Christian positions fail to provide a foundation by which a valid epistemology, metaphysic, or ethic can be held in a consistent, non-arbitrary way.