Update to this story.

SAN FRANCISCO, CA — San Francisco Archbishop Salvatore Cordileone has responded that, despite criticism from political leaders in his home state, he will attend the March for Marriage this week, because his position requires him to act as a defender of the Catholic faith.

In a letter released today, Cordileone wrote that he is required “as a bishop, to proclaim the truth—the whole truth—about the human person and God’s will for our flourishing … especially the truth about marriage as the conjugal union of husband and wife,” Cordileone wrote. “That is what I will be doing on June 19th.”

Political figures from Nancy Pelosi to San Francisco Mayor Ed Lee to California Lt. Governor Gavin Newsom had written to Cordileone, asking him not to take part in the second annual march in Washington, D.C., on Thursday.

Pelosi, who supports marriage redefinition, called the march “venom masquerading as virtue.”

“We share our love of the Catholic faith and our city of San Francisco,” she wrote to her archbishop. But she said some of the event’s participants show “hate and disdain” for homosexuals.