OLD TOWN — In a “last stand” effort to preserve the definition of marriage as a union between a man and a woman, the Roman Catholic Diocese of Portland held a series of meetings across the state over the weekend urging people to evangelize and explain to friends and neighbors why same-sex marriage should be rejected.

David and Angela Franks, a married couple from Massachusetts, led a meeting at the Knights of Columbus Hall in Old Town on Sunday. Both hold doctorate degrees in theology from Boston schools. Their presentation was titled “Defending Marriage in the Public Square,” an offshoot of Bishop Richard Malone’s March pastoral letter, “Marriage: Yesterday … Today … Always.”

Mainers will go to the polls Nov. 6 to vote on a referendum that would allow same-sex couples to marry in Maine. In 2009, voters repealed a law allowing same-sex couples to marry six months after the Legislature passed the bill, which was signed into law by then-Gov. John Baldacci.

The Franks outlined what constitutes marriage as “the loving union of one man and one woman, publicly vowed, oriented toward the procreation and education of children and the good of the spouses.”

“Marriage is about children,” Angela Franks said. “Marriage is this relationship in which children are given the optimal environment in which to be raised.”

Because marriage is inherently about children, governments took an interest in licensing and regulating marriages, the couple argued. Because same-sex couples cannot produce offspring, the definition should not be changed to include them, the couple said.

Marriage between a man and a woman makes biological, societal and economic sense, the couple argued, and altering the definition of marriage would only serve to “scramble the social script.”

The differences between male and female seen across the spectrum of plant and animal life are natural indications of what should constitute marriage, the Frankses said.

“It’s not crude, it’s beautiful,” David Franks said, referring to sexual relations between a male and female. “It makes sense.”

David Franks said during the meeting that Mainers are forced to consider a second time in three years whether to recognize same-sex marriage.

“Is that equality?” Franks asked. “No, it’s violence upon us. … We’re being forced to say, ‘Yeah, it constitutes marriage.’”

The Franks said Catholics are challenged in defending the definition of marriage because many of them have homosexual friends or family members who want to carry their sexual “preferences, attractions and desires” into a marriage, and Catholics risk being called “bigots” if they push back to defend their definition of marriage.

“The Church wants to use her gifts to bolster human reason, try to blow away some of the ideological smoke and get at what’s really going on,” David Franks said.

Matt McTighe, campaign manager for Mainers United for Marriage, said Sunday afternoon that the Catholic Church was attempting to stop a change that wouldn’t affect the church.

The question on November’s ballot will ask voters whether they want the state to issue marriage licenses to same-sex couples. The law contains a religious exemption, which states that religious institutions can choose not to perform or host a same-sex marriage.

McTighe said the church’s focus on marriage as a step toward procreation and rearing a successful offspring “undercuts the fundamental core of what marriage really is. … There are thousands of couples that can’t or choose not to have kids, and of course we allow those couples to marry.”

“Should we be allowing the Catholic Church to determine what the state’s definition is?” McTighe asked.

McTighe, himself a Catholic, said that the church is concerned about the sacrament of marriage, while the ballot question is concerned with the issuance of marriage licenses. He argued that allowing same-sex couples to marry and raise children would neither weaken the family unit nor harm society.

“Every couple should have that same freedom to enter in that lifelong commitment with the person they love,” regardless of sexual orientation, McTighe said.

McTighe’s defintion of marriage: “You meet somebody, you fall in love with them, you make the commitment with them, and then you get married.”