Because we can’t help but make choices in those areas. Do we follow one of the world’s established religions, or do we live our lives without religious considerations? How do we decide what’s right and what’s wrong? How do we know the things we know? What is the best way to govern a country?
These questions are hard to escape. We can ignore politics, but politics doesn’t ignore us. We have to decide what is right to do. We claim to know certain things. I once say a bumper sticker that said “Sleep in on Sunday and Save Ten Percent.” Should we do that, or do we live in accordance with the teachings of a religion? Not to decide, is to decide. Our actions speak for us, even when our words do not.
In each of these cases, one can back up to a far more minimal conception of what is required. But then it is very difficult to go anywhere with the argument in its subsequent steps. If B can be accepted only in a fairly minimal sense, then it is not at all obvious that D is true. Conversely, in the sense in which D is obviously true, A2 and B are just as obviously false. So the argument gains no traction.
To say this is not to say that it would not be desirable for Christians to have better, fuller knowledge on some of these points; nor is it to say that such knowledge is not available. But the hinge of the argument is the claim in A2 that Christians would need a set of G-beliefs in order to have a personal relationship with God. And Drange gives no good reason to think that this claim is both (a) true and (b) substantive enough to support his subsequent chain of reasoning.