The letter said that being Catholic can be "challenging" and the high school leaders voiced hope that the action does not dishearten parents, staff, and students.
The high school is affiliated with the Brothers of Holy Cross and its bylaws state that its Catholic identity is to be "at all times maintained" and that education in the faith is "a mission priority."
"We are committed to educating our students in the tenets of the Catholic faith with an emphasis on the Holy Cross tradition," said the school's letter.
The letter voiced respect for the position of those at Brebeuf Jesuit Preparatory School and said there are differences in the schools' respective situations.
"Brebeuf is sponsored by the Jesuits while Cathedral is merely affiliated with the Brothers of Holy Cross. Because Brebeuf is a specific ministry of the Jesuits, their canonical and nonprofit status is different than ours. Therefore, the two schools cannot function the same way if Cathedral were to receive a similar decree as Brebeuf," the school said.
School leaders at Brebeuf had said that despite the archdiocese's decision "our identity as a Catholic Jesuit institution remains unchanged." They said that to follow the instruction from the archdiocese "would not only violate our informed conscience on this particular matter, but also set a concerning precedent for future interference in the school's operations and other governance matters that Brebeuf Jesuit leadership has historically had the sole right and privilege to address and decide."
The archdiocese first made the request to Brebeuf two years before.
The Code of Canon Law recognizes the diocesan bishop's responsibility to ensure that religion teachers are "outstanding in true doctrine, in the witness of their Christian life, and in their teaching ability." The diocesan bishop has the right to approve religion teachers and, "if religious or moral considerations require it, the right to remove them or to demand that they be removed."
Fr. Brian Paulson, S.J., head of the Jesuits' Midwest Province, said he recognized the archbishop's instruction to be "his prudential judgement of the application of canon law" regarding his responsibility for Catholic education and oversight of faith and morals in his archdiocese.
The Archdiocese of Indianapolis has previously addressed a similar issues at another school.
In August 2018, Shelley Fitzgerald, a guidance counselor at Roncalli High School in Indianapolis, was placed on paid administrative leave. Fitzgerald, an employee of an archdiocesan school, had attempted to contract a same-sex marriage in 2014.
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The Indianapolis high school cases drew significant comment from LGBT activists and the prominent Jesuit commentator Father James Martin, editor-at-large of America Magazine, who claimed that the action targets "LGBT people" and not "straight teachers."
Morals clauses at Catholic schools have been a target of some activist groups, including the dissenting Catholic Equally Blessed Coalition. The coalition has received several low-six figure grants from the Arcus Foundation to back LGBT activists and to counter the Catholic Church.
One coalition member, New Ways Ministry, gave Martin its Bridge Building Award in 2016.