The quote specifies God, not "a voice claiming to be God". I'm not sure what evidence would be required, but presumably there must be some, or why would you follow any revelation?
The quote specifies God, not "a voice claiming to be God".
In that case, the Christian's obvious and correct response is "that wouldn't happen", and responding to that with "yeah, but what if? huh? huh?" is unlikely to lead to a fruitful conversation. Penn's original thought experiment is simply broken.
Replace "God" by "rationality" and consider the question asked of yourself. How do you respond?
Happy New Year! Here's the latest and greatest installment of rationality quotes. Remember: