It may be a useful technique at times, but I think it's more productive to establish as much common ground as possible, then highlight where each person diverges.
In most cases, divergence among rational people can be traced to different priorities. I think the same would apply if discussing religion with a rational religious person (something I don't think is totally impossible).
For example, here's my argument about why I'm an atheist:
God gave humans rational minds where he gave animals teeth and claws. He surely didn't give us rational minds so that we would stop using rationality. Thus, God intended humans to be atheists at first. If He intended humans to be faithful (which you claim) then he intended it not as a counter to rationality but as the result of the application of rationality. Just as the bird is meant to flap its wings in order to alight, the human is meant to exercise the full strength of his rationality in order to thrive.
By contrast, God also created angels, who lack the problem of rationality-inspired doubt. They are in essence "faith robots" who are incapable of achieving faith, since they start out with it. Such a being is really little more than a slave or automaton.
As we all know, the plight of humans toward faith is a far higher cause than if we were simply pre-programmed. God intended humans to have a journey whose reward at the end (a solid, rational, unwavering faith) is not something that can be gained by reciting something as a child or sitting unquestioningly in a pew, but must (and should) be earned via the most earnest rational inquiry one can muster.
Thus I, an atheist, am completely confident that if God one day wishes me to be faithful I will discover that faith through the same process of rationality that currently makes me an atheist. QED.