Judaism has, outside some mystical currents, less of an emphasis on "well, do you really believe?" than in Christianity, and more of an emphasis on rule-following (and studying how to navigate those rules) as the basic bargain between God and man.
EDIT: My bad, I missed that Neumann asked to be baptised, so he wasn't going back to the Judaism of his ancestors through his Pascal's Wager-esque step.
EDIT: My bad, I missed that Neumann asked to be baptised, so he wasn't going back to the Judaism of his ancestors through his Pascal's Wager-esque step.