Here are three myths that dominate the marriage debate.

Myth 1: Same-sex couples who want to marry simply want the same rights as others.

In fact, this isn’t what homosexuals want at all.

They could even now participate in the institution of marriage, defined as it always has been as a union between a man and a woman. What homosexual activists really want is for marriage to be redefined to honor their relationships.

They aren’t the first.

Polygamists wanted marriage to be redefined to fit their circumstances. The courts refused them. Consanguine lovers — relatives who want to marry each other — have also asked that the institution of marriage be redefined to fit their circumstances. The courts refused them, too.

That’s because marriage has a particular meaning.

Polygamists and consanguine lovers argued that marriage’s definition was something like: “The sanction and financial benefits society gives to people who are committed to living together because of their love.”

The courts answered: “No, marriage is the sanction and financial benefits society gives to a man and woman because, by and large, such unions will produce children and raise them in a stable, sound environment.”

Just like homosexuals do now, polygamists and consanguine lovers argued that this definition is discriminatory.

The courts agreed. Marriage is discriminatory. Marriage laws discriminate a great deal: by age (you can be too young to marry), by marital status (you must be divorced to marry if you were previously married) and by proximity (your prospective spouse must be present to marry). The financial benefits of marriage are also discriminatory: against roommates, brothers and sisters who share a home, and nursing-home residents who share an address.

Marriage discriminates because marriage is precious and must be protected and promoted.

We know what will happen as soon as same-sex couples have a right to “marry.”

Those polygamists and consanguine lovers who aren’t able to marry will come back to the courts and say, “Well, what about us? It turns out that we were right after all. Marriage is the sanction and financial benefits society gives to people who are committed to living a loving life together.” What will the courts be able say to them then?

Myth 2: Religious beliefs and human traditions make people uncomfortable with homosexuality, but there’s no real difference between homosexual and heterosexual couples.

In fact, the difference is clear in a number of ways.

Medically, heterosexual sex is a natural and normal activity that does no harm to a couple under ordinary circumstances. Male homosexual sex injures its participants regularly — both because the rectum is damaged during penetration and because only the vagina is biologically equipped to be a safe receptacle for semen.

Psychologically, the benefits love and marriage bring to men and women are well documented. Yet even in countries where homosexuality is an accepted, integrated part of society, homosexuals suffer higher rates of depression and suicide than the general public.

And children are bound to suffer if their parents are part of the homosexual scene. From the Village People song “YMCA” to the Showtime television show “Queer as Folk,” homosexual culture has long celebrated sex with teens. One of the most-often searched for pornography terms on the Internet is a homosexual a slang word for underage teenage boys. In The Gay Report, by homosexual researchers Karla Jay and Allen Young, the authors report data showing that 73% of homosexuals surveyed had at some time had sex with boys 16 to 19 years of age or younger.

Myth 3: Homosexual marriage is inevitable, so we might as well make the best of it.

“All that is necessary for the triumph of evil is that good men do nothing,” said Edmund Burke. And Pope John Paul II said, “Families will be the first victims of the evils that they have done no more than note with indifference.”

There are simple things each of us can do: Before voting, check Vote-smart.org for candidates’ positions on marriage. Find legislators’ addresses and write to them about this important issue. Write letters to the editor whenever you see an article make the mistakes above.

And pray. In his apostolic letter on the Rosary, Pope John Paul II called for daily Rosaries for the defense of the family.

Ultimately, the truth will win out. But the better we spread the truth, the less damage we will have to suffer before its victory.