A month ago I wrote a piece making fun of Newt Gingrich's wild ideas about space exploration. In the interest of fairness, it is time to make fun of what are now the two leading Republican candidates ideas, not about space, but about heaven.

One might think that the religious beliefs of political candidates should remain off limits in public discourse. I don't think so, at least not when candidates wear their religion on their sleeves.

Candidates should have the right to keep their religious views private, but in the current climate essentially none of them actually do so. Rick Santorum has gone so far as to argue that John Kennedy's strict confirmation of the separation of church and state, which many consider one of the pillars of American democracy, should be discarded. In this case, it is all the more important to explore his theological views.

More generally, should we not be able to question whether the beliefs of the religion publicly espoused by a candidate may reflect on candidate's judgment and their ability to distinguish sense from nonsense? Why is it acceptable to dissect Newt Gingrich's fanciful plans for making the Moon a 51st state but not his implicit suggestion that Pope John Paul II was responsible, via divine intervention, for the fall of communism?

Not all religious beliefs are currently so immune. Christine O'Donnell, the Tea Party Senate candidate from Delaware, had her campaign torpedoed when it was revealed she had "dabbled in witchcraft" as a teenager. This, in spite of the fact that, as my colleague and Templeton prizewinner Paul Davies reminded me at the time, Wiccan theology is in many senses no less strange than Christian theology.

This issue is particularly relevant in this election season because the two leading Republican candidates, Mitt Romney and Rick Santorum, are an enthusiastic Mormon and a fundamentalist Catholic respectively.

The bible is full of dubious scientific impossibilities, from Jonah living inside a whale, to the Sun standing still in the sky for Joshua. But while the miracles at the foundation of the Mormon Church may be no more or less believable in an a priori sense than those attributed to mainstream Judeo-Christianity, they are clearly more suspect. Joseph Smith was previously tried for the crime of claiming to falsely find lost treasure when he then claimed to discover golden tablets buried under a tree in upstate New York in the 19th century, and with the aid of an angel translates them into 17th century English, and then the original tablets miraculously disappear. Among the beliefs that followed include the claim that native American tribes represent the lost tribe of Israel and that Jesus Christ also conveniently visited North America.

Shouldn't we wonder about the judgment of anyone who buys that story without doubt, especially when that person is vying for our trust as commander in chief?

It should be admitted that Mitt Romney does not openly defend the dubious claims of Mormonism while declaring his faith on the campaign trail. Rick Santorum on the other hand is more explicit about his own unique brand of Catholicism. He is most well-known for his religious opposition to both contraception and abortion, which have led him to make ridiculous statements regarding how birth control leads to more abortions for example, which bring back memories Pope Benedict's famous claim that condom use in Africa would increase the likelihood of AIDS.

However, his theological beliefs have led him to more bizarre beliefs that transcend even the doctrines of the Roman Catholic Church. Unlike the official statements of the Vatican, Santorum has argued strenuously that his theology is incompatible with the facts of biological evolution, and he has spearheaded calls for the insertion of religious based nonsense, labeled "intelligent design" into public school science curricula. Perhaps even more worrisome is his "end of days" theological belief that "Satan has his sights on the United States of America," as the former Senator put it in a speech a few years ago.

When a person's religious beliefs cause him to deny the evidence of science, or for whom public policy morphs into a battle with the devil, shouldn't that be a subject for discussion and debate?

As Richard Dawkins has emphasized, you wouldn't want to go to a doctor who subscribed to the Stork theory of reproduction, so why should we not focus on the actual content of the publicly espoused beliefs held by politicians?

Both Romney and Santorum no doubt gained their faith by exposure to their respective religions as children. Nevertheless, as adults we should amass sufficient tools of critical thinking to know which stories to keep and which to discard. It thus seems fair game to openly and directly ask Mr. Romney and Mr. Santorum to outline the specifics of their beliefs about the sacred as well as the profane, in order to more fully probe the character and intellect anyone who proposes to lead this nation. To do any less is to be negligent in our duties as citizens.