The secret formula?
The new card, from major financial institution Bank Leumi, won't work its magic on Shabbat. And even on non-holy days, it will never function at a store that stays open on Shabbat.
"It's an initiative that started among religious people," Bank Leumi public-relations officer Guy Keider said in a statement.
The makers of the card want to make it unusable at stores that do not keep the Sabbath, primarily so non-observant retailers may feel the pinch of staying open on Shabbat. That's because many observant merchants have complained in the past that they are being driven out of business by competitors who do trade on Shabbat.
The card's chief backers include Rabbi Rafael Halperin, owner of a chain of opticians, and Knesset member Meir Porush. Porush believes that the new credit card will attract hundreds of thousands of people "for whom the Sabbath is close to their hearts."
For Jews who strictly observe the Sabbath, commerce transactions are forbidden between Friday night and Saturday night.
The ultra-Orthodox community in Israel is estimated at about 800,000 people, and the plan's proponents say that up to a quarter of them may end up using the new card.
Presently, most ultra-Orthodox Jews in Israel do not own a credit card. All it would take is an added microchip to turn a regular credit card into a shomer-Shabbat one.
Nevertheless, the card's forecasted potential profits are 10 million shekels ($2.3 million) a month.
Benefits for Sabbath-observant stores are not unprecedented. Car-insurers, for example, give discounts to clients who affirm they will not drive on Shabbat; and some public pools offer reduced six-days-a-week memberships.
Some kinks may still have to be worked out for the new cards. International travelers would need to find out if they'd face problems abroad due to time-zone changes, and measures need to be in place so that the card can be used during life-and-death emergencies on the Sabbath (called pikuach nefesh).
What's the biggest upshot for the card?
If an Orthodox Jew's wallet is stolen on Friday afternoon, even the most secular of Jews can't fraudulently use the card for at least 25 hours.