"Telling the truth is a value you must protect all the time," says Garry Wills, author of "Papal Sin: Structures of Deceit." "The teaching part of the church is relying on these old silly arguments; they ring hollower and hollower.''

Wills could never be accused of faintheartedness. He argues that celibacywas imposed on priests in the fourth century to compete with the authorityof desert ascetics; that women were excluded from the priesthood based onGreek and Jewish notions of female inferiority and impurity; and that banson contraception are not supported by Scripture.

The papacy, he insists, is more concerned with preserving consistency thanrecognizing truthful teachings. Such a "structure of deceit'' is creating aCatholic majority that loves Pope John Paul II but ignores his dictates oncontraception, abortion, and masturbation, he contends.

In conversation, Wills speaks gruffly and sparingly. He praises his Catholiceducation, although he says, "The church gave the impression to me it neverchanged an iota, that everything we did in the parish was done in the earlychurch. That's so absurd it's easy to make fun of it.''

Not only has the church changed, it has changed without losing credibility,Wills says, citing the switch from the Latin Mass.

Wills decided to write ``Papal Sin'' while finishing a recent biography ofSt. Augustine, whom he considers a model of truth-telling, and whilefollowing the case of a Texas priest accused of molesting children. Hedevotes a chapter to his claim that institutional deceit made it difficultfor priests to police themselves, writing: "Looking the other way is adeeply ingrained habit and necessity, a tactic of survival, for men whoselives are honeycombed with furtive acts.''

Wills described Pope John Paul II as "an engaging, courageous person'' whohas fostered openness toward other faiths. But he argues the current pope'sallegiance to the past has put him at odds with social and cultural change.For example, he said, John Paul's "conception of Mary is what makes himthink that women should be subordinate. Mary was obedient. He said womenshouldn't want to be priests because Mary wasn't a priest.''

However harsh his critique, Wills believes he is a good Catholic. "Papalismis not Catholicism,'' he says. "It never occurred to me to leave thechurch.'' Wills doesn't pull any punches in his new book, ``Papal Sin,'' asthese excerpts show:

On excluding women from the priesthood:

"It is not so much that women are clamoring to become priests (especially asthe priesthood currently exists), but the perpetuation of this ban keepsalive the whole ideological substructure on which it is based. It is thelast fierce bastion where the great Christian lie about women has entrencheditself."

On celibacy:

"Almost all the priests who left in the massive hemorrhage of 1970's and 1980'sleft to marry. The homosexual priests stayed, which meant that theirproportion of the whole went up even when their absolute numbers stayed thesame. And now even that absolute number is rising. Many observers suspectthat John Paul's real legacy to his church is a gay priesthood."

On contraception:

"Most people thought that New York Cardinal O'Connor's opposition to thedistribution of condoms for AIDS prevention was aimed at homosexuals.

Itturns out it is meant to threaten the life of married people as well. Thecondom is more sinful than even death by AIDS."