Pope cites 'urgent' need to avoid confusion over gay unions VATICAN CITY (AP) - Pope Benedict XVI said Thursday there was an "urgent" need to avoid confusion over gay unions and other common-law partnerships, and stressed that only marriage between men and women could be the basis for a healthy society. Benedict also said the 1968 encyclical "Humanae Vitae," which defined the church's opposition to artificial birth control, remains relevant today. He said the physical differences between men and women were not just biological happenstance, but had a far more profound significance _ that of coming together to create new life. The pope spoke to members of the Pontifical John Paul II Institute for Studies on Marriage and Family, an institute founded by the late pope to promote church teachings on the sanctity of marriage and family. During an audience to mark the institute's 25th anniversary, Benedict called love and marriage between man and woman an "authentic good for society." "There is a special urgency today to avoid confusion with other types of unions based on a weak love," he said. "Only the rock of total and irrevocable love between a man and woman is able to build a society that is home to all men." He did not specify gay unions in his remarks, but Benedict has frequently spoken out about the need to preserve the sanctity of marriage and has condemned same-sex unions as anarchic "pseudo-matrimony." When he was Cardinal Joseph Ratzinger and prefect of the Congregation for the Doctrine of the Faith, the pope also spearheaded a 2003 Vatican campaign against same-sex unions, issuing guidelines for Catholic politicians to oppose laws granting legal rights to gay couples.