"I think for example of that statement that appears in many versions of the ontological argument, namely 'The Greatest Conceivable Being is a possible being.' Many (including me) would claim to know this statement, but surely many others would dispute such a claim. And I see no way of proving the statement apart from showing that the Greatest Conceivable Being is actual (all actual beings are possible beings). Nevertheless, if this being seems to me to be a possible being, and if I have apparently answered successfully all the known arguments to the contrary, then I know to be plausible the statement, 'The Greatest Conceivable Being is a possible being.' Accordingly, I can rationally believe the statement, and I can use it as a premise in a successful theistic proof." Stephen T. Davis, God, Reason, and Theistic Proofs (Grand Rapids, MI: Wm. B. Eerdmans, 1997), 7.
I think Davis' point is a salient one. Namely, that one can be justified in believing in certain theistic arguments, like the ontological argument, even if you cannot rationally compel a skeptic to believe it. Too many young apologists are obsessed with offering proof such that no rational person could refuse to believe in God. However admirable and lofty a goal, faith, while not devoid of evidence or blind, is nonetheless not contingent upon rational compulsion. Whatever rational compulsion is, it is not sufficient for biblical faith. Rationality itself, however, is important for the believer. So Davis' contribution here is that believers can be quite rational in holding to certain theistic premises and arguments. What do you think?