Well, I’ve studied a lot, so I’m not very likely to lose my beliefs.
I’d still be an orthodox trinitarian theist looking for an (orthodox two-nature) Incarnation and Passion (and probably a preceding history similar to that of Israel in the OT) if the Gospels (and Epistles) were somehow conclusively proven wrong about Jesus’ resurrection.
Most alterations to specific details reported in canonical texts have no bearing on any of that either–if Luke sends off in his research for the Imperial census records, and someone at the office accidentally sends back a note where Joseph (and a young Jesus, as the Apostate Emperor Julian once argued!) registered for taxation in the Big Census of 8 AD, leading Luke to report that it happened in the day of the governorship of Kyrenius–not a big deal to me. Minor historical accidents happen. Worst case of persistent forgery and misreportage by the Evangelists?–I’m still an orthodox trinitarian theist looking for an Incarnation, Passion and Resurrection.
We were already warned about evil miraculous demonstrations that would deceive, if it were possible, even the elect. Christ Himself in the Gospels seems to think miracles distract too much from what He’s trying to say. Even people granted miraculous power and authority by Christ to do good in His name may at heart still be rebels rejected by Christ! So miracles by themselves are of no special theological concern to me. (Interesting and curious yes, and maybe problematic in other ways, but not a threat to my beliefs.)
I’m waaaay too well taught by C. S. Lewis to worry about hyper-advanced extra-terrestrials being any kind of threat to my beliefs. Worst case would be aliens with ironclad proof that they (or aliens of their acquaintance) were pretending to be YHWH and/or Jesus all along–their mere sayso could just as easily be opportunistic lies! Eh, back to being “only” an orthodox trinitarian theist expecting an Incarnation etc.
If atheists could decisively show that people don’t exist but are only illusions of automatic reaction and counterreaction, that would be problematic (and I’ve had some atheists try this against me on occasion!)–but it would be first and foremost problematic for them and their own arguments, since I would literally have no good reason to accept that what they were arguing was true! And I have carefully studied metaphysics well enough to know where the existence of human rational action capability leads when all the math is added up: to theism, to supernatural theism, to binitarian theism, to ethical binitarian theism, to ethical trinitarian theism, to orthodox Christian universalism, to an expectation of the Incarnation, Passion, etc. I believe Christianity is true because I believe in atheists! (Although more particularly because I believe in the existence of the agnostic whom I love the most. )
But personal suffering is often about faith in another sense. I live in unending pain every waking hour. (And I’m exhausted by stress dreams and nightmares every night.) It sucks. I don’t like it. Sometimes it isn’t so prevalent, but other times it surges. Regardless of what I may rationally believe, I often feel like God doesn’t care about me or doesn’t exist at all.
My faith in the sense of trusting God doesn’t always hold up well under torment. But I just have to keep reminding myself that no one thinks very clearly under strong emotional stress, and to just hang on until it passes and otherwise remind myself of what I have come to know. (Such as that much of my suffering, maybe even all my chronic suffering, isn’t actually unfair to me, however much it may feel that way sometimes. And I was warned by God ahead of time it would keep on being this bad if I chose to do what He was asking of me. It was clearly worth doing then, and still clearly was worth doing, and will always clearly have been worth doing.)
There is a whole other concept of unfaithfulness, of course: and that’s sin.
Yeah, in that regard I routinely lose my faith in God. But that isn’t anyone’s fault but my own.
(I acknowledge original sin effects, and how they slant my behavior, and I penitently–and often impatiently!–look to be free of those someday. But I also take personal responsibility for my misbehavior. What can be excused and cured will be excused and cured, but that leaves over what has to be forgiven and repented of.)