Since I published my book on heaven, I have had several non-Christians request that I provide evidence for heaven (i.e. evidence to persuade them). Moreover, there seems to be a common expectation that the provision of this kind of evidence is somehow a requirement or expectation for the writing of a book on heaven. I have replied by pointing out that I have written books (and many articles) defending the truth of theism and Christianity and that I am simply engaged in a different topic here, i.e. how a Christian ought to think about heaven given the truth of Christian doctrine.
Despite this fact, the misbegotten requests still come. It is misbegotten for two reasons. First, as I said, I’ve already independently provided evidence elsewhere for the truth of (and rationality of belief in) Christian doctrine, so this is neither the time nor the place.
Second, those making the request generally seem to be of the opinion that the legitimacy of the discourse depends on the provision of independent evidence to persuade them. In other words, a book on heaven is only justifiable if independent evidence to persuade the skeptic of heaven’s existence is provided alongside the book.
This is not the case elsewhere, however. Imagine, for example, that I write a book titled Electronic Voting and the Crisis of Democracy. In the book I aim to show that the increasing dependence on paperless electronic technology is imperiling a healthy, functioning democracy. Now imagine that folks coming upon my book were to object: but why accept democracy? Where do you justify democracy? The fact is that I am not obliged to defend democracy before I write a book critiquing the impact of electronic voting on democracy. And it is simply mistaken to think otherwise.
And so it is here. Just as a person can assume the superiority of democracy as a presupposition to writing a book defending an aspect of democracy, so one can write a book assuming the truth of Christian doctrine on heaven as a presupposition to writing a book defending a particular understanding of heaven.