Setting aside for the moment presuppositionalism, I'd also be interested in whether, from a natural theology approach, one can argue that it's immoral not to believe in God. Or at least not as moral. Conversely, that it's positively moral to believe in God. Or (to make an even more modest argument) unwise and imprudential (to coin a term) not to believe in God.I wonder if an argument can be made that we're rationally obligated to want and desire God to exist and from there argue that since no argument has ever been formulated that disproves all gods (including the Christian God), that therefore one ought to provisionally believe in a God with the traditional "omni" attributes. This isn't an argument for the existence of God. Rather it's an argument for BELIEF in God (either on rational grounds, and/or moral grounds). To borrow from Kant's argument from morality, only with an afterlife where a perfectly omniscient judge who can omnipotently mete out justice (presumably tempering it with mercy) can individuals and society ground moral behavior. And therefore, it would be a moral duty to promote belief in God both in others and in oneself (even if only provisionally).Arguments fashioned/patterned on the above would be more modest than the various moral arguments for God's *existence* (e.g. HERE or Here). One goal for making such arguments for *belief* (rather than *existence*) would be to encourage people to exercise their wills to provisionally believe in God in a volitional manner (even if, there is a sense in which all men already do know God, as per Van Tillian presuppsitionalism). It wouldn't involve having to deal with the problem of *direct* doxastic voluntarism. But it can pave the way for *indirect* doxastic voluntarism by which people—having been given reason to pursuit such line of thinking—can immerse themselves with apologetical literature which may make them more open and receptive. And so eventually leading them to actually and consciously believing in God's existence. Not merely for pragmatic or prudential reasons as originally argued at the beginning above. Calvinism and it's doctrine of the universal knowledge of God, total depravity and of regeneration, need not deny or undermine the psychological reality that people's beliefs often do go through a process of change and that God often works *through* and *with* such changes, and with arguments like those above. God can use bad arguments as well as weak or even good but (i.e. yet) modest arguments to bring people to faith. Sometimes to slowly peel away layers of self-deception. Regeneration and conversion doesn't always automatically result in an instantaneous radical way of thinking. Sometimes it's a slow process.I'm a Van Tillian presupper and so believe that non-Christians really do believe in God deep down. However, it's not always productive to repeatedly assert that truth "as fact" to non-Christians (e.g. atheists). I don't think that they are always outright lying when they say they really don't believe in God. That's because it's hidden under layers of sinful self-deception and sinful lack of self-reflection/examination. Sometimes I wonder if atheists encountering Van Tillians feel their non-belief is both justified and reinforced/confirmed when they examine themselves (at least superficially) and conclude Van Tillians are wrong since "they really don't believe in God" (or so they think at the surface level of their consciousnesses). I think Van Tillians like myself need to find more and better ways to bring that deeper inescapable knowledge of God—which all non-Christians have—closer to the surface. I think arguments for *belief* in God may help.