At the height of the Vietnam War, a bumper sticker began to appear on cars and pickup trucks across the country. The message was: "America! Love It or Leave It."

The drivers of these mobile flag-waving units were protesting the protesters. To them, criticism of government policy, government actions, was the same as disloyalty to the country. The United States was not a homeland but a government hierarchy. Americans were not citizens but more like employees of major corporations. They could either do what the boss said or punch out for good.

The bumper sticker wasn't quite accurate. The word "Love" was all wrong. Their message was not about love of country but about obedience to authority. The slogan should have read: Government! Obey It or Leave It.

I thought about that bumper sticker for the first time in years when the Vatican recently threatened to dismiss 24 nuns and four men in religious communities. They were among the 94 Catholics who had signed an ad in The New York Times stating the obvious, that "a diversity of opinions regarding abortion exists among committed Catholics."

On the spectrum of protest, this ad was as mild as a letter to King George III that might have begun "Dear King, About the matter of tea . . . " It was a cautious statement of the facts: the fact that a large number of Catholic theologians believe that abortion "though tragic can sometimes be a moral choice"; the fact that only 11 percent of Catholics surveyed disapprove of abortion in all circumstances. The men and women who signed this ad were not signing in support of abortion itself, but in support of open discussion of the issue.

This particular statement had been passed around for almost a year by Catholics for a Free Choice. It only gained momentum and signers during the election at the height of controversy over politicians and religion, particularly the religion of one political woman, Geraldine Ferraro.

Ferraro was a special target of the church. Bishops such as Law and O'Connor and Krol watched Ferraro go to church on Sunday and talk pro-choice on Monday. She became a challenge to authority, proof that they had lost control over Catholic women, proof that individual Catholics could make decisions that were not always in line with those of the hierarchy, and yet remain Catholics.

The ad finally placed in the Oct. 7 New York Times was not just a veiled defense of Ferraro but also of individual conscience under attack by the bishops. It was a public statement about pluralism within the heart of the church -- nuns, theologians, priests -- on this issue. As such, it is no surprise that the increasingly hard-line hierarchy would fire back an ultimatum to the co-signers: CatholiAuthority, Obey It or Leave It.

Many are sympathetic to the church hierarchy's demand for "clarity" among its members. The hierarchy wants to present a united front that neither waffles nor admits ambivalence. This is why it criticizes lay leaders such as Ferraro. This is why it demands that its religious community members, nuns and brothers and priests, keep that front solid even when it is a facade.

But there is in this controversy the implication that nuns and priests, like cowed employees, should say only what they are told as long as they receive support from the church. It is a curious portrait of nuns as people who were hired to serve rather than "called" to service. It's a portrait of the church as a corporation rather than a community, a club that one can belong to as long as one follows the rules, rather than a family with room for disagreement and feuding and belonging.

The attempt to silence these women and men is much more serious than the loss of 28 "jobs." The Vatican has said that it is no longer permissible to admit to differences of opinion among Catholics about abortion or, for that matter, liberation theology or even birth control. It is choosing instead, issue by issue, to expel diversity in the name of obedience.

This small incident may well be another watershed experience for American Catholics. The church of Vatican II, a more open, egalitarian, diverse family, is disappearing. In the name of purity, of rigidity, the Vatican is tightening up the qualifications for belonging. It isn't just the members of the religious orders who have to choose between their consciences, their individual beliefs, and their church. Many others who love it may be forced to leave it.