I'm an atheist, but it hardly matters.
I believe what I believe based on critical thinking about evidence I have in front of me. If that evidence were to shift a significant amount, i'd be stupid not to change my belief.
If several absolute miracles happened in front of me, someone I know prayed for something impossible and got it etc etc etc, I might question my sanity just a little but i'd surely have to change my mind.
Likewise, if I were Christian, then some kind of undisputable historical evidence was uncovered that proved the bible was completely false and that Jesus never existed, how could I possibly continue to believe what I believe.