Yes, it is.
Many Catholic schools require their employees — whether they are Catholic or not — to follow Roman Catholic teaching, at least in their public lives. As a result, some gay teachers have been fired for marrying someone of the same sex. And other employees could also be fired for any public words or deeds contrary to Church teaching, even though the employee might not be Catholic.
Yes, same-sex marriage is contrary to Catholic teaching. And if a Catholic priest legally marries a man, the Church will dismiss him from the clerical state, and he will no longer have the role of a priest. Actually, if a Catholic priest legally marries a woman, he will receive the same penalty, but that is beside the point. The Church has the right to require Her ministers to adhere to Catholic teaching.
However, when this is extended to the non-Catholic employees, who have no ministerial role, a conflict with Church law occurs.
“Can. 748 n. 1. All persons are bound to seek the truth in those things which regard God and his Church and by virtue of divine law are bound by the obligation and possess the right of embracing and observing the truth which they have come to know.
“n. 2. No one is ever permitted to coerce persons to embrace the Catholic faith against their conscience.”
Threatening any and all non-Catholic employees with firing, if they do not live their public lives according to the Catholic faith, is a type of coercion. Essentially, many Catholic dioceses and Catholic schools are, in a limited manner, attempting “to coerce persons to embrace the Catholic faith against their conscience.” And that is contrary to Church law and contrary to the moral law.
People have a right (Can. 748 n. 1) to seek the truth on matters of faith and morals, and to embrace that truth in accord with their own conscience. And that right applies even if the person has a sincere but mistaken conscience on some matter. They are still bound, under divine law, by their own conscience. And they still possess the right to embrace and observe their own understanding of religious and moral truth. “Conscience frequently errs from invincible ignorance without losing its dignity.” [Second Vatican Council, Gaudium et Spes, 16; See also Catechism of the Catholic Church n. 160]
In my opinion, other than persons who perform true ministerial roles or who teach religion, Catholic schools should not be permitted to fire employees who fail to live according to Catholic teaching. It is contrary to Canon law. It is coercion to violate one’s conscience. It is coercion to live by religious teachings to which one does not subscribe.
There is also an issue of hypocrisy here. Very many employees of dioceses and parishes have used artificial contraception during their marriages, in clear violation of Catholic teaching. And they are never fired for doing so. Employees of Catholic schools are often known to be in violation of Catholic teaching, in various ways, in their personal lives, and they are not fired. In my view, it is only because same-sex marriage is a current issue of political contention between the Church and secular society that these firings take place. These teachers are not fired for violating Church teaching, but for violating a political stance taken by the Church in society at large.
Furthermore, if every Catholic school in the U.S. fired every employee who violated Church teaching in any serious way, the schools would have to shut down for lack of staff. Most Mass-going Communion-receiving Catholics could not meet the standard that schools set for non-Catholic employees, that they live according to Catholic teachings. For the Church to hold non-Catholic employees to a standard that is not applied, and would typically not be met, by most Mass-going Communion-receiving Catholics is ridiculous.
Catholic school employees have a right to freedom of religion — morally and under the Bill of Rights of the U.S. Constitution — and they should not be required to sign away that right, in whole or in part, in order to teach a non-religious subject in a Catholic school. If a school wishes all employees to adhere to Catholic teaching, they should only hire believing and practicing Catholics. When they choose to hire non-Catholic employees, they cannot assert their limited legal right to require ministers to adhere to Church teaching. For a non-Catholic employee cannot reasonably be considered a minster of the Catholic faith.
The Catholic Church rightly says to society, “Please don’t pass laws requiring us to violate our consciences.” And then, hypocritically, some Catholic dioceses require their non-Catholic employees to violate their consciences by living as if they were Catholic.
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