'To legalize marriage between two people of the same sex would enshrine in the law the principle that mothers and fathers are interchangeable or irrelevant.'

San Francisco Archbishop Salvatore Cordileone chairs the United States Conference of Catholic Bishops' Subcommittee for the Promotion and Defense of Marriage. Here are his views on the subject in response to questions from USA TODAY:

Q: What is the greatest threat posed by allowing gays and lesbians to marry?
A:The better question is: What is the great good in protecting the public understanding that to make a marriage you need a husband and a wife? I can illustrate my point with a personal example. When I was Bishop of Oakland, I lived at a residence at the Cathedral, overlooking Lake Merritt. It's very beautiful. But across the lake, as the streets go from 1st Avenue to the city limits at 100th Avenue, those 100 blocks consist entirely of inner city neighborhoods plagued by fatherlessness and all the suffering it produces: youth violence, poverty, drugs, crime, gangs, school dropouts, and incredibly high murder rates. Walk those blocks and you can see with your own eyes: A society that is careless about getting fathers and mothers together to raise their children in one loving family is causing enormous heartache.
To legalize marriage between two people of the same sex would enshrine in the law the principle that mothers and fathers are interchangeable or irrelevant, and that marriage is essentially an institution about adults, not children; marriage would mean nothing more than giving adults recognition and benefits in their most significant relationship.
How can we do this to our children?

Q: If the Supreme Court opens the floodgates to gay marriage in California (or beyond), what will be the result?
A: If the Supreme Court overturns Prop 8, this will not go down in history as the Loving v. Virginia but as the Roe v. Wade decision of our generation.
No matter what the Supreme Court rules, this debate is not over. Marriage is too important and the issues raised by treating same-gender unions as marriages are too fundamental to just go away. Just as Roe v. Wade did not end the conversation about abortion, so a ruling that tries to import same-sex marriage into our Constitution is not going to end the marriage debate, but intensify it.
We will have a bitterly polarized country divided on the marriage issue for years if not generations to come.

Q: Why is this of such importance to children?
A: Why has virtually every known civilization across time and history recognized the need to bring together men and women to make and raise the next generation together? Clearly something important is at stake, or human beings of such different cultures, histories and religions would not come up with the basic idea of marriage as a male-female union over and over again.
... When we as a culture abandon that idea and ideal, children suffer, communities suffer, women suffer, and men are dehumanized by being told they aren't important to the project of family life.
Modern social science evidence generally supports the idea that the ideal for a child is a married mother and father. The scientific study of children raised by two men or two women is in its infancy ... several recent studies ... are painting a less sanguine portrait that some professional organizations have yet acknowledged about whether two dads can make up for the absence of a mom, or vice versa.
We all know heroic single mothers who do a great job raising their kids (just as there are gay people who take good care of their children). But the question of the definition of marriage is not about success or failure in parenting in any particular case.
The job of single mothers is hard precisely because we aren't as a society raising boys to believe they need to become faithful husbands and fathers, men who care for and protect their children, and the mother of their children, in marriage. And we aren't raising girls to be the kind of young women with the high standards and the self-worth to expect and appreciate such men, and not to settle for less.

Q: How would the allegation that opponents are bigoted lead to their rights being abridged?
A: Notice the first right being taken away: the right of 7 million Californians who devoted time and treasure to the democratic process, to vote for our shared vision of marriage. Taking away people's right to vote on marriage is not in itself a small thing.
But the larger picture that's becoming increasingly clear is that this is not just a debate about what two people do in their private life, it's a debate about a new public norm: Either you support redefining marriage to include two people of the same sex or you stand accused by law and culture of bigotry and discrimination.
If you want to know what this new public legal and social norm stigmatizing traditional believers will mean for real people, ask David and Tanya Parker, who objected to their kindergarten son being taught about same sex marriage after the Massachusetts Supreme Court legalized it in that state and wanted to pull him out of class for that lesson. He was arrested and handcuffed for trying to protect his son's education, and they were told they had no right to do so.
Ask the good people of Ocean Grove Methodist camp in New Jersey that had part of its tax-exempt status rescinded because they don't allow same-sex civil union ceremonies on their grounds. Ask Tammy Schulz of Illinois, who adopted four children (including a sibling group) through Evangelical Child Family Services — which was shut down because it refuses to place children with same-sex couples. (The same thing has happened in Illinois, Boston and Washington, D.C., to Catholic Charities adoption services). ... Ask the doctor in San Diego County who did not want to personally create a fatherless child through artificial insemination, and was punished by the courts.... Ask Amy Rudnicki who testified in the Colorado Legislature recently that if Catholic Charities is shut out of the adoption business by new legislation, her family will lose the child they expected to adopt this year. ... Nobody is better off if religious adoption agencies are excluded from helping find good homes for abused and neglected children, but governments are doing this because the principle of "anti-discrimination" is trumping liberty and compassion. ...
When people say that opposition to gay marriage is discriminatory, like opposition to interracial marriage, they cannot also say their views won't hurt anybody else. They seek to create and enforce a new moral and legal norm that stigmatizes those who view marriage as the union of husband and wife. ... It's not kind, and it doesn't seem to lead to a "live and let live" pluralism.

Q: You have spoken of gay marriage as a "natural impossibility." But in terms of procreation, how does it differ from opposite-sex couples who are elderly or infertile?
A: Our bodies have meaning. The conjugal union of a man and a woman is not a factory to produce babies; marriage seeks to create a total community of love, a "one flesh" union of mind, heart and body that includes a willingness to care for any children their bodily union makes together.
Two men and two women can certainly have a close loving committed emotional relationship, but they can never ever join as one flesh in the unique way a husband and wife do.
Infertility is, as you point out, part of the natural life cycle of marriage (people age!), as well as a challenge and disappointment some husbands and wives have to go through. People who have been married for 50 years are no less married because they can no longer have children.
Adoption can be a wonderful happy ending for children who lack even one parent able or willing to care for them. But notice, when a man and woman cannot have children together, that's an accident of circumstances, the exception to the rule. When a husband and wife adopt, they are mirroring the pattern set in nature itself. ...
Treating same-sex relationships as marriage is the final severing by government of the natural link between marriage and the great task of bringing together male and female to make and raise the next generation together in love.

Q: Is it particularly difficult for you to play a leading role against gay marriage in a place like San Francisco? Does it change your relationship with gay congregants?
A: Truthfully, I am really excited to be in San Francisco. I remember the first time I saw the city as a boy when our family drove up from San Diego to meet my father who was unloading his tuna boat here. ... To me San Francisco was and is The City! It represents vibrant, pulsating, creative, cosmopolitan life and I love it. Of course I realize many people in San Francisco disagree with the church's teachings on marriage and sex, but there is also a very deeply embedded Catholic culture here with many people who understand and cherish the church's teachings. My job as an archbishop is to teach the truths of our faith and the truths of the natural moral law, and whatever challenges that entails I embrace with enthusiasm.
We can learn to respect each other across differences and even to love one another. That's my hope anyway. And my job description.

Q: Has it become more difficult to oppose gay marriage over the years? Does it seem the tide is turning against you?
A:There is a problem here – an injustice, really – in the way that some people are so often identified by what they are against. Opposition to same-sex marriage is a natural consequence of what we are for, i.e., preserving the traditional, natural understanding of marriage in the culture and in the law. But of course people who are for the redefinition of marriage to include two men or two women are also against something: They are against protecting the social and legal understanding that marriage is the union of a husband and wife who can give children a mother and father.
So there are really two different ideas of marriage being debated in our society right now, and they cannot coexist: Marriage is either a conjugal union of a man and a woman designed to unite husband and wife to each other and to any children who may come from their union, or it is a relationship for the mutual benefit of adults which the state recognizes and to which it grants certain benefits. Whoever is for one, is opposed to the other. ...
Those of us who favor preserving the traditional understanding of marriage do not do so because we want people who experience attraction to their same sex to suffer. We recognize and respect the equal human dignity of everyone. Everyone should be treated equally, but it is not discrimination to treat differently things that are different. Marriage really is unique for a reason.

Q: Do you have friends or family members who are gay? How do you balance your public policy positions with those relationships?
A: Of course! I am a Baby Boomer, and I grew up in Southern California. The larger question you raise about my relationships with people I care about is: How can we love each other across deep differences in moral views? The answer I have found is that when we want to stay in relationship, we can and do. Love finds a way. When we want to exclude or hate, we find each other's views literally intolerable.
Of course, it helps that my friends know me, directly and unfiltered through any other source. When you know someone personally, it's much harder to rely on stereotyped or media-created images. It's a lot harder to be hateful or prejudiced against a person, or group of people, that one knows personally. When there is personal knowledge and human interaction, the barriers of prejudice and pre-conceived ideas come down.

Q: What are your main goals: Supreme Court, lower courts, state legislatures, public opinion, religious liberty?
A: My main goal is none of these. I'm a faith leader, and my main goal is to seek to create a Catholic community in San Francisco where people know what the church teaches and uses this knowledge to guide their own lives and get to heaven. I want to help people understand the truth of natural marriage and, for people of my own faith, the deeper, theological, even mystical meaning of marriage as designed by God.
Using words, though, is only one way of teaching. Usually one's actions speak louder than words. So there is a place for public manifestations of principle. The civil rights marches of the '60s are a good example of that. Yes, they were a way to agitate for long overdue political change, but they also had a teaching effect in that they got people to think about the injustices of racism.
Engaging with the broader culture is also part of my teaching role as an archbishop, and of course my right as U.S. citizen.

Q: Are you worried about the recent trend in courts and states going against you? How best to stop that trend?
A: The natural law has a power written on the human heart that doesn't go away.
Notice how there is no controversy in this country now over the evil of Jim Crow laws. Shortly after the Civil Rights Act the cultural change was complete. This is because it was the right thing to do. The truth cannot be suppressed indefinitely.
Draw a contrast here with the pro-life movement: After the Roe decision, it was commonly thought that our society would soon easily accept the legitimacy of abortion. But what has happened? The pro-life movement is stronger now, 40 years later, than it ever has been. This is because of the truth: Abortion is the killing of an innocent human life. That is not a matter of opinion or religious belief; it is a simple fact that cannot be denied.
The same principle applies with marriage: It is simply a natural fact that you need a man and a woman to make a marriage and that a child's heart longs for the love of both his or her mother and father. Even if the Supreme Court rules against this truth, the controversy will not die out, as it hasn't on the abortion issue.
The problem is, the longer a society operates in denial of the truth, the greater is the harm that will be done. The examples of the racist policies and practices of the past in our own country make this clear, as does all the harm that abortion has done to women and all those in her network of relationships.
With marriage, we have to consider the harm that will be caused by enshrining in the law the principle that children do not need a mother and a father. The circumstances of our struggles change but the truth does not.