A friend of mine wanted answers to the big questions and found them all in one place: The Catholic faith.

After his conversion, he broke the news to an aunt, who exclaimed: “Why would you do that? I'm a Protestant and I can do anything I like.”

Not a few Catholics share her attitude. Particularly in the area of sexuality, they would prefer a church that issued only permission slips and a pope obligingly silent about norms of behavior. Garry Wills, who in recent years has tirelessly informed us about the shortcomings of Pope John Paul II, has a new best seller that caters to such attitudes. Why I am a Catholic, No. 7 on the New York Times list for hard-cover nonfiction as of press time, is a self-esteem manual for Catholics who want to tune out the magisterium and buy into a sexual revolution which long ago failed on its own terms.

This is a very annoying book. It has a veneer of scholarship that, on closer examination, proves bogus. Its centerpiece is a highly tendentious history of the papacy meant to discredit as many popes as possible. You can get the same skewed versions of these historical episodes — Pope Zosimus endorses Pelagianism! Popes Liberius and Honorius turn heretic! — by visiting Protestant fundamentalist Web sites.

When making highly debatable claims, such as that there was no bishop of Rome until well into the second century or that the papal primacy was not recognized until centuries later, Wills never mentions the literary evidence to the contrary. Instead, he takes at face value the claims of “progressive” historians who, like himself, want to cut the magisterium down to size.

It is not difficult to find even liberal Catholic scholars who disagree with Wills about the early primacy of Rome. In his recent history of the papacy, Saints and Sinners, Eamon Duffy writes that the apostolic succession of the chair of Peter “rests on traditions which stretch back to the very beginning of the written records of Christianity.” Duffy quotes St. Irenaeus, who, around 180, invoked the Church of Rome as the “great and illustrious Church” to which, “on account of its commanding position, every church, that is faithful everywhere, must resort.” St. Irenaeus also supplies us with the earliest list of popes after Peter (Linus, Cletus, Clement and so on) about which Wills is silent.

So much for an early phantom papacy. When it comes to subsequent popes, Wills is shocked — shocked — to find not a few careerists, sycophants, politicians and bad administrators. But Christ did not exclude the papacy when he said that the Church would be a mixture of wheat and tares until the end of time. He did, however, establish the Church as a teaching authority and handed the keys to Peter and his successors.

Christ established the Church as a teaching authority. This is where Garry Wills begs to differ.

This is where Wills begs to differ. He wants a church that endorses contraception, homosexual sex, serial marriage and other items on the menu of political correctness. The magisterium, as defined by the Second Vatican Council, will not do this, so Wills has to manufacture his own authority that he can adhere to and still call himself Catholic. And what is this authority? It boils down to his own conscience and the thwarted intentions, as Wills reads them, of the most liberal bishops at the Second Vatican Council.

Wills rightly emphasizes Vatican II's endorsement of “freedom of conscience.” But he does not mention the council's insistence on an antecedent duty to form our conscience according to “objective standards of moral conduct.” For a Catholic, the teachings of the magisterium are a definitive, although not exhaustive, guide to such standards.

Without directly saying so, Wills flatly rejects what Lumen Gentium, a council document he is happy to quote in other contexts, teaches about the authority of the pope and bishops in this regard. Instead, he turns to that convenient fogging agent, the “spirit of Vatican II,” defined in this case as what the most radical theologians had hoped to accomplish at the council. This invisible authority, needless to say, urges the conscience of all Catholics to follow the path of least resistance when it comes to difficult moral issues.

An irony that escapes Wills is that among the more liberal bishops at Vatican II was the future Pope John Paul II, who had a large influence on its most “radical” documents. John Paul's pontificate has been a rich unfolding of the Council's teachings. But dissidents like Wills are so focused on a handful of sexual issues that they cannot see this. Nor do they seem to notice that those Protestant denominations that have caved in on these issues are the ones whose numbers have declined most drastically.

The teachings of the Church are not always easy. After all, Christ came as a sign of contradiction. But these teachings exist for a good reason, and it would be a good thing if Catholics like Wills would stop regarding them as arbitrary rules imposed from the outside. They are, rather, signposts — and based not simply on Revelation, but also on a profound reading of the human person.

George Sim Johnston, author of Did Darwin Get it Right?, writes from New York City.