KENTFIELD (CBS SF) – Five members of the Dominican Sisters of Mary order walked out of their classes last week at Marin Catholic High School to protest the sponsors of a program intended to protect gay and lesbian teens from bullying.

According to Phil Matier in the San Francisco Chronicle’s Matier & Ross column, at issue was Friday’s annual Day of Silence, promoted by the Gay, Lesbian and Straight Education Network.

The group has major corporate sponsors, including McDonald’s, Target, Google and Disney/ABC. It bills itself as a group of “students, parents, and teachers that tries to effect positive change in schools,” but the nuns said they see it as anti-Catholic.

The walkout came a day after 100 prominent local Catholics took out a full-page ad in The Chronicle calling on the pope to oust San Francisco Archbishop Salvatore Cordileone.

Officials at Marin Catholic tried to diffuse the situation by sending a letter to parents, saying it was “a challenging day on our campus resulting in both students and faculty feeling confused about our mission.”

The school did not participate in the Day of Silence. Instead, a morning prayer was read over the school’s PA system. School administrators said it was linked on Facebook to the campaign by the Gay, Lesbian and Straight Education Network, which administrators in their letter called “an activist group with which we are not affiliated.”

When some Marin Catholic students began handing out Day of Silence-related stickers and flyers, that was when the nuns decided to walk out. “[We] felt compromised, offended and uncomfortable,” Sister Clare Marie, one of the teachers, wrote in an email to her students.

Kari Hudnell, a spokeswoman for the Gay, Lesbian and Straight Education Network, said the group is not actively promoting homosexuality in the classroom. “We are not trying to convert anyone,” Hudnell told The Chronicle. “We are just trying to make sure schools are a safe environment for all kids.”

This is just the latest controversy involving Catholic schools in the Bay Area since Archbishop Cordileone tried to get teachers to sign off on a morality clause that among other things characterized homosexual relations as “gravely evil.”