Catholic education in the United States will be substantially stronger if dioceses follow the lead of bishops in California, Hawaii and Ohio, who are requiring their teachers to both know and adhere to Catholic teaching.

Archbishop Salvatore Cordileone of San Francisco is among the latest to declare Catholic schoolteachers’ work a ministry, a designation that has great significance for the mission of Catholic education, as well as for protecting Catholic schools from lawsuits and violations of religious freedom.

Others who have sought similar improvements to teacher contracts and policies include Bishop Michael Barber of Oakland, Calif., Bishop Robert Vasa of Santa Rosa, Calif., Archbishop Dennis Schnurr of Cincinnati, Bishop Frederick Campbell of Columbus, Ohio, and Bishop Larry Silva of Honolulu.

But critics have asked: Where’s the justice in requiring teachers to behave morally outside of the classroom? Ought teachers be held to the highest standards as “ministers” of the faith?

In San Francisco, the media and lawmakers are predictably opposed to any restriction on hiring teachers who openly live in same-sex “marriages.” Last month, students and parents held a candlelight vigil outside of St. Mary’s Cathedral, defending the rights of teachers to dissent. And the dissident organization Call to Action has launched a petition against “morality clauses” in Catholic-school contracts.

Also opposed are Catholic teachers’ unions, which worry that dioceses might gain too much power over collective bargaining. That’s because, in 2012, the Supreme Court ruled in Hosanna-Tabor v. EEOC that the First Amendment allows a “ministerial exception” to nondiscrimination laws, as long as a teacher functions as a “minister” for a religious school at least part of the day. It allows a Catholic school to discipline an employee for violating the school’s Catholic mission without fear of a lawsuit.

The unions are right about the law, and it’s one important reason why the “ministry” designation is essential. Our Catholic bishops have the rightful authority to defend Catholic teaching and protect the Catholic mission of Catholic schools, which includes ensuring that curriculum, employment policies, health benefits and other concerns remain consistent with Catholic teaching and that teachers are good role models for students. No union should be able to compromise that authority.

Moreover, given increasing attempts by government at all levels to restrict religious freedom, it is vital for the defense of Catholic schools that teachers are covered as ministerial employees.

But this is more than a legal question. Catholic education is truly a ministry in which all teachers perform — or ought to perform — a vital religious function. Catholic schools are not simply places of secular education with a moral environment and religious instruction for students. Their primary objective should be the whole formation of students as Christians, and all teaching ought to be presented in the light of the truth revealed through Jesus Christ and his Church.

Canon law states clearly that Catholic “teachers must be outstanding in true doctrine and uprightness of life” (Canon 803). And the U.S. bishops have reminded Catholic school leaders that this mandate applies to teachers in all disciplines:

“Recruit teachers who are practicing Catholics, who can understand and accept the teachings of the Catholic Church and the moral demands of the Gospel and who can contribute to the achievement of the school’s Catholic identity and apostolic goals. … The distinctive Catholic identity and mission of the Catholic school also depend on the efforts and example of the whole faculty. … All teachers in Catholic schools share in the catechetical ministry” (National Directory for Catechesis, pp. 231, 233).

 Why should this be so? Because worship and teaching the faith are perhaps the two most fundamental activities of all religions. And in a Catholic school, all knowledge is understood as a reflection of God’s truth and creation; our faith gives meaning to knowledge that would otherwise be distorted.

Catholic schoolteachers, then, must conform to the truths of the Catholic faith. They teach not only by word, but by example, and they are to be models to their students of “the ideal Person,” Jesus Christ (Congregation for Catholic Education, Lay Catholics in Schools: Witnesses to Faith, 32).

When they violate Catholic morality and do so publicly, teachers invite scandal as much as sinful priests and parents. Precisely because they assume the role of educator, teachers have the high expectation of moral uprightness.

There’s nothing easy in this, of course, and dioceses that rightly expect high standards face significant challenges identifying qualified employees. But what wonderful gifts to the Church are faithful Catholic educators! With great love for the teacher’s vocation, Pope Benedict beautifully invited American educators in 2008 to help young people “know and love the One you have encountered, whose truth and goodness you have experienced with joy.”

Now, what could be a greater ministry than that?

 Patrick J. Reilly is president of the Cardinal Newman Society, which promotes and defends faithful Catholic education.