DENVER (CNA)—A Colorado proposal to recognize same-sex civil unions is a “dangerous and unjust” effort to redefine marriage, warns Bishop James Conley, the apostolic administrator of the Archdiocese of Denver.

“We do not know the long-term consequences of creating a parallel for marriage, distinct from its ancient and natural meaning. But we do know they will be severe,” Bishop Conley said in his Jan. 11 column for the Denver Catholic Register.

He said that a renewed legislative push for civil unions in the state threatens to erode the “unique status” of marriage as between one man and one woman.

This upcoming weekend, the Colorado Catholic Conference will ask Catholics to sign postcards to legislators in opposition to the move.

Bishop Conley urged people to participate in the campaign because “it allows each of us to speak the truth: to ask the government to respect the plan for marriage God has given us.”

“Doing so protects children, protects marriage and, ultimately, protects the common good of all of us.”

He warned that recognizing civil unions for same-sex couples would allow them to adopt children and infringe on religious liberties for many groups. Some also view civil unions as “a stepping stone” to endorsing polygamous relationships.

“Redefining marriage means that government will try to redefine truth,” he said.

He then cited Bishop Salvatore Cordileone of Oakland, Calif., who chairs the U.S. bishops’ conference Subcommittee on Marriage.

Bishop Cordileone recently said that civil unions can “in no way” be considered a permissible compromise or an advance for the common good.

“(I)nstead, they directly violate principles of justice and accelerate the push to redefine marriage itself.”

Marriage is “among the oldest human institutions,” Bishop Conley emphasized, saying that “the communion of husband and wife is a unique reality that has no true parallel.”

The Denver bishop observed that, throughout history, political thinkers have believed that protecting families is at the heart of the government’s responsibility.

He said that laws which protect marriage ensure that families can provide children “the right to two parents, a mother and a father, who can love them and care for them.”

Marriage laws also require men to treat women with dignity, he noted, adding that the “exclusive and permanent bond” of a married man and woman cannot be redesigned by “legal dictate.”

Bishop Conley pointed to Church teaching that Catholics must treat individuals with same-sex attraction with “dignity and love.” Those who have homosexual inclinations are not evil, though the inclination is a “tragic distortion of the great gift of sexuality God has given us.”

The essentials problem with civil-union laws, he explained, is that they “endorse and sanction that distortion by suggesting that homosexual relationships are equivalent to marriage.”

The Catholic bishops of Colorado have also stressed that opposition to civil unions is not voiced out of desire to deny fundamental civil rights and is not a condemnation of homosexual people.

“We affirm what our Church teaches: namely that we must treat our homosexual sisters and brothers with dignity and love, as we would all God’s children,” they said in a joint statement.

In 2006, Colorado voters defeated a same-sex civil-unions ballot measure by 52% to 47%.

Last year the Democrat-controlled Colorado Senate passed a civil-unions bill for both same-sex and opposite-sex couples by a vote of 23-12. The bill died in a committee of the Republican-controlled House of Representatives, where the Republicans have a one-vote majority.

The bill is planned to be reintroduced.

In recent decades, the state has become a hub for homosexual-advocacy movements. Its wealthy backers include multimillionaire Coloradan Tim Gill, who is pursuing a strategy of targeting opponents of homosexual political causes at the local level to eliminate future leaders opposed to his efforts.

In April 2011, Gill’s lawyer, Ted Trimpa, told Denver’s Fox 31 News that Gill could spend as much as $2 million in 2012 state political contests to shift the state House to Democrat control.

A group of Republicans called Coloradans for Freedom has also joined the push for civil unions.