No impact.
People of faith don't need the physical ark to affirm their beliefs. And you could parade every relic (and person) from the bible in front of a atheist and they would just call every bit of it fake.
Atheist: "I denial your very existence!"
Jesus: "I'm standing right in front of you." - wave hand in atheist's face - "Hello ..."
So in your absurd example, does this man claiming to be Jesus have any way of demonstrating his status as such? Or is he just some guy waving at me going "Hey, i'm jesus, now you MUST believe me!"
What reason do you have for thinking that when presented with rational and conclusive evidence, Atheists would still not believe in something? Because your statement flies right in the face of why a great deal of atheists actually are atheists.
Please, explain yourself.