Tuesday’s announcement that the Vatican has appointed Archbishop Jose Gomez of San Antonio as coadjutor and successor to Cardinal Roger M. Mahony is a significant event both for America’s largest Roman Catholic diocese and for California.

The selection of the Mexican-born Gomez is a decisive break with the past on at least two counts. The first is easy to discern: No U.S. prelate of Latino heritage ever has worn a cardinal’s red hat. That departure from tradition makes sense. There are 5 million Catholics in the Archdiocese of Los Angeles -- twice the number in New York -- and about 70% are Latinos. By the end of this decade, most U.S. Catholics will trace their heritage to Mexico or Central or South America.

As Mahony -- a fluent Spanish speaker with a deep and abiding concern for issues vital to Latinos -- affirmed Tuesday, he actively urged the Vatican to select a Latino as his successor. In Denver, where he first served as an auxiliary bishop, Gomez played a key role in bringing white and Latino Catholics together, and more recently, in San Antonio he not only sharply increased the number of seminarians but also promoted a highly regarded bilingual program of priestly formation.

The other signal Rome may be sending with this appointment may be disruptive. Los Angeles’ new coadjutor bishop and -- barring the unforeseeable -- future cardinal has spent most of his priestly career as a member of Opus Dei, the secretive and controversial Catholic movement with its roots deep in Franco’s Spain. Opus Dei, which stresses doctrinal orthodoxy and an ultramontane loyalty to the papacy, was a great favorite of Pope John Paul II and is a favorite of Pope Benedict XVI. The former created a “personal prelature” for the organization, so that its roughly 90,000 members scattered around the world report directly to their own bishop in Rome and he reports directly to the pope. No other such arrangement exists in the church. John Paul also canonized the movement’s Spanish founder, Josemaria Escriva, who, according to close associates, on occasion expressed admiration for Hitler’s antagonism to Bolshevism and skepticism that 6 million Jews perished in the Holocaust.

You don’t have to be a fan of the dreadful “Da Vinci Code” to find Opus Dei a trifle creepy. Its secrecy is legendary, as is its predilection for discredited “mortifications” of the flesh, such as wearing the celice -- a spiked metal circlet applied to the thigh until it draws blood -- or self-flagellation with a knotted cord.

Politically, Opus Dei’s sympathies generally extend to the authoritarian. It provided Franco with Cabinet ministers and supported Augusto Pinochet in Chile.

Gomez’s connections to the movement couldn’t be deeper. Born in Monterrey, Mexico, he studied theology at the University of Navarra, which is rather like Opus Dei’s Harvard. Ordained as a priest of the movement, he later served as one of its superiors, Vicar of the Delegation of Texas. Though there are 22 Opus Dei bishops among the church’s 27,811 prelates, Gomez is the only one who is a full member of the order.

In a recent pastoral letter to San Antonio Catholics, Gomez wrote, “My approach and understanding . . . owes a great deal to my appreciation of the spirituality of St. Josemaria Escriva.”

The changes for Los Angeles’ Catholics may be wrenching. Mahony is the last of the politically progressive, pastorally centered American prelates selected in the wake of Vatican II. Gomez belongs to a traditionalist generation. The cardinal, for example, has promoted lay participation in every canonically permissible kind of ministry. Gomez, like the pope, is said to favor clearer and more traditional divisions between the lay and clerical roles.

Some also are bound to be wary of his close association with Archbishop Charles J. Chaput, his mentor in Denver and one of the church’s most stridently conservative voices. Chaput, for example, feels that Catholic office-holders who cast pro-choice votes ought to be denied Communion. He recently gave an address in Texas in which he argued that John F. Kennedy was wrong in insisting on separation of church and state.

In California, a staunchly Democratic state where one out of every four people is Catholic, that sort of confrontational leadership could have serious consequences.

tim.rutten@latimes.com