Catholics seeking to build up a strong culture of marriage must focus on promoting a healthy understanding of it rather than simply fighting against attacks, according to the author of a new book on discussing marriage.

"Our goal isn't to prevent same-sex couples from marrying," said William B. May, president of Catholics for the Common Good, a San Francisco-based lay apostolate that seeks to evangelize the culture.

Rather, he explained, the goal is to promote marriage, the fundamental social institution that unites the parents of children who come into the world from their union.

May told CNA in an early November interview that one of the biggest problems in promoting a healthy culture of marriage is that the meaning of marriage has been obscured.

Many people think that marriage is simply "the public recognition of a committed relationship," an adult-centered union that is about happiness and personal fulfillment "rather than the foundation of the family," he explained.

But in reality, marriage unites a man, a woman and any children born from their union, he said, noting that this fundamental relationship has been recognized by every culture, society and religion throughout history, each in their own way.

In his new book, "Getting the Marriage Conversation Right: A Guide for Effective Dialogue" (Emmaus Road, $5.95), May explains how to successfully discuss marriage and presents the results of research conducted on marriage and family life.

"There are a lot of things that are contributing to the crisis of marriage," he acknowledged, pointing to no-fault divorce, contraception and the sexual revolution as examples. As a result, Catholics problematically find themselves working to defend marriage "rather than promote the reality of what marriage is."

The fundamental question is, "Do we need an institution that unites kids with their moms and dads?" he said, underscoring that marriage is the only institution that does this.

The nature of marriage is "a fact that can only be recognized and not changed," he said. It has nothing to do with homosexuality, but is "stamped in our very nature."

When understood in this way, May argued that it becomes clear marriage cannot simply be expanded to include same-sex couples, because doing so would actually redefine its essence. 

May pointed to recent ballot measures in Maine, Maryland and Washington state, where voters recently approved efforts to redefine marriage.

The ballot language in these states dealt largely with marriage licenses, May said, and it was not apparent to many voters that the initiatives would actually be eliminating the only civil recognition of a union joining mothers and fathers.

"Getting the Marriage Conversation Right" discusses the breakdown in the culture of marriage and the importance of building it back up. It also covers frequently asked questions about marriage, commenting on topics such as homosexual adoption, claims of discrimination, effects of freedom of consciences and the relationship between civil and religious marriage.

In addition, the book delves into the fundamental right of children to know and be cared for by their fathers and mothers, as much as possible.

May pointed to the natural human interest in one's ancestors, as well as the way that adopted individuals often feel a desire to search for their biological parents.

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"We have a desire for connection," he explained. "It's part of our identity. It's part of who we are."

He also noted that redefining marriage comes with dire consequences because it removes the most basic institution that safeguards children.

Promoting marriage for the sake of children is important, he explained, observing that both liberal and conservative think tanks recognize marriage as a key way of "dealing with the root causes of poverty and fatherless homes."

However, this becomes impossible once marriage is redefined, he said, because the institution loses its connection to children, and initiatives to promote fathers as being important and necessary become viewed as discrimination under the law.

In Massachusetts, kindergarten students now read books telling them that marriage is not about the family, he noted.

May suggested that his new book can be used as a practical guide to dialogue about marriage and can be helpful for parents, priests and Catholic school teachers to explain marriage to children.

It fosters "reality-based thinking" and helps marriage advocates act on the offensive, rather than being constantly on the defensive, he said.

Ultimately, there is a need to develop programs and curricula encouraging young people to get married before having children, he said.  No one wants their children to grow up to be single parents, but society does not encourage strong and healthy marriages.

The push to restore marriage "starts around the family dinner table," he emphasized.