Bishop Salvatore Cordileone has compared gay marriage to male breastfeeding.

Cordileone, an outspoken opponent of gay nuptials who in 2008 backed passage of Proposition 8, California's ban, was recently installed as the leader of the Archdiocese of San Francisco. He is also the chairman of the U.S. Conference of Catholic Bishops' (USCCB) Subcommittee for the Promotion and Defense of Marriage.

(Related: Catholic bishops file briefs in Supreme Court gay marriage cases.)

Cordileone made the comparison in comments to the United Kingdom's Catholic Herald.

He cautioned against using the term “gay marriage” because talking about it could lead people to being fooled into believing it is possible. Cordileone then compared such unions to another impossibility: “Legislating for the right of the same sex to marry is like legalizing male breastfeeding.”

In response to opponents who have called him homophobic, Cordileone answered: “All our detractors can do is call us names. Big deal if they shout at us or throw insults!”

Among U.S. Catholic bishops, Cordileone is among the most outspoken on the issue.