The United States Conference of Catholic Bishops (USCCB) has issued a letter, urging the House of Representatives “to preserve and protect” the “vital institution” of marriage and support the Marriage Protection Amendment.

The proposed legislation, H.J. Res. 106, would amend the United States Constitution to define marriage as consisting only of the union of a man and a woman. It is expected to be taken up in the House later this week.

In the letter Sept. 28, USCCB president Bishop Wilton D. Gregory said the bishops’ concern for marriage is not just “a Catholic concern.”

“We share it with believers and non-believers, Christians and non-Christians alike, simply because this understanding is part of the common moral heritage of humanity," said the bishop of Belleville.

"It is precisely this moral heritage that must be protected today from a small but vocal minority that would alter the definition of marriage by making same-sex unions the legal equivalent of marriage," he said.

"A same-sex union is not equivalent to marriage. It is not based on the natural complementarity of male and female; it cannot cooperate with God to create new life; it cannot be a true conjugal union," he continued.

He stated that recent court action in various states has placed marriage – “a basic human institution” – under serious attack and in grave danger.

While civil and Church laws regulate marriage, “it did not originate from either the Church or state, but from God,” Bishop Gregory said. “Accordingly, the bishops believe that neither Church nor the state can alter the basic meaning and structure of marriage.

"Marriage, as properly understood, is more than a lifestyle choice," he continued. "It is an interpersonal relationship with public significance. It makes a unique and irreplaceable contribution to the common good of society when it fulfills its natural, God-given purposes, namely, to bring children into the world and care for them and to provide a way for a man and a woman to seek each other's good in a committed, lifetime relationship."

The USCCB has been working on the marriage issue, supporting efforts at the state level to preserve marriage as the union of a man and a woman.

A year ago its Administrative Committee called for efforts at all levels of government, including support for a federal constitutional amendment. This past July Bishop Gregory wrote to the Senate in support of the Federal Marriage Amendment.