Here are four basic points that I think apologists should make: (1) There is a variety of strong evidence that a Supreme Being — that is, God — exists. (2) There is also strong evidence for the historicity of the Gospels, and in particular their core message that Jesus is God. (3) Pascal’s Wager makes a lot of sense. (4) Finally, simply as a matter of philosophy and good living, Christianity is powerfully attractive.
While (2) alone wins the day and is the sine qua non of apologetics, getting there might be easier in conjunction with the other three. Thus, sometimes a major hurdle is getting someone to believe in God at all (1); once that is accomplished, it becomes possible to persuade someone that this God is the Trinity of Christianity. And, since there will always be some room for doubt, it is valuable for the apologist to persuade the potential convert that he should bear in mind throughout the process (3) that the downsides of not believing wrongly are much greater than the downsides of believing wrongly, and that the upsides of believing rightly are much greater than the upsides of correct disbelief. As for comparing the relative merits of believing incorrectly with even correct disbelief, this is where (4) can be useful. That is, the Christian life is not a bad one, even in wholly secular terms; and so Pascal is right that the rational course, considering all the possibilities, is to cultivate one’s faith.
Note: Consider a four-quadrant approach to explaining Pascal’s Wager: A is belief and God exists (value is +100); B is belief and God doesn’t exist (indeterminate value, but much less than +100 and much more than -100); C is disbelief and God exists (value is -100); and D is disbelief and God doesn’t exist (another indeterminate value, but again much less than +100 and much more than -100). So there are six possible comparisons of different quadrants. Now C is worse than B, and A is greater than D, because of the +/-100 weighings. D is obviously better than C, and A is obviously better than B, and A is obviously better than C — but these combinations are not really even at issue. The remaining comparison, of B and D, is the one where it’s a relatively close call, and lesson (4) helps teach that B might be better than D.