In order for me to believe in a deity, I would require verifiable evidence supporting such a discovery that would survive experimentation and the peer review process without being disproven or better explained by some other answer. From there, I would need Christianity's philosophy to change into one that wasn't exclusionary and didn't contradict and/or discourage the use of reason, but in fact promoted it. Finally, I would require a similar level of evidentiary proof showing that Christianity's claims were in fact correct as opposed to any other specific religious claims or just simple deism. So basically I'd only be able to accept the Christian moniker if almost everything about it changed and we could verify that a god did exist. But even then, most likely, I would see no reason to label myself specifically as a Christian - I can only say that I might have turned out to be one in such a world.