We’re extremely disappointed in President Obama’s decision to declare his support for the redefinition of marriage, bestowing the authority of his presidency on a cause that would upend thousands of years of tradition crossing all cultures, societies and religions.

The definition of marriage as the union of one man and one woman has endured throughout the millennia, with marriage serving as an essential building block of society.

It’s a definition that should not be subject to change based on polling numbers or on the popularity of a particular cause at a given moment in time.

Cardinal Dolan, in a statement issued in his role as president of the U.S. Conference of Catholic Bishops, said he was “deeply saddened” by the president’s May 9 comments that his views on same-sex marriage had evolved and that he now backs such unions.

While stressing that the bishops stand ready to support the president in measures designed to strengthen marriage and the family, the cardinal said they “cannot be silent in the face of words or actions that would undermine the institution of marriage, the very cornerstone of our society.”

In a commencement speech at The Catholic University of America, the cardinal urged graduates to support efforts to uphold traditional marriage, saying that the union of a man and a woman in marriage “is so essential to the order of the common good that its very definition is ingrained into our interior dictionary, that its protection and flourishing is the aim of enlightened culture.”

The Archdiocese of Washington, D.C., in its own statement, said the word “marriage” describes the exclusive and lifelong union of one man and one woman open to generating and nurturing children. “Other unions exist, but they are not marriage,” the statement said.

Obama made his comments on marriage in a television interview three days after Vice President Joseph Biden, a Catholic, said on television that he was “absolutely comfortable” with same-sex couples marrying.

That view, of course, does not follow Catholic Church teaching, which upholds the sanctity of traditional marriage as being only between one man and one woman.

The remarks of the president and vice president do, however, follow the administration’s policies regarding marriage, in particular its decision last year to stop defending the Defense of Marriage Act in court cases. That act, passed 15 years ago by a Republican Congress and signed by President Bill Clinton, a Democrat, officially defines marriage as a legal union between one man and one woman and specifies that no state is required to recognize the same-sex union of another state. So these latest “endorsements” by Obama and Biden are not really a surprise.

In an election year, the redefinition of marriage can be a tricky one. While polls show that support for redefinition has grown in recent years, the country remains evenly split on the issue, making it hard to predict whether the president’s views on the matter will have an effect one way or the other on the election’s outcome.

But that is not the point. As we said, marriage should not be defined by polls or by the direction of the wind.

We join Cardinal Dolan in praying that the president and his administration “act justly to uphold and protect marriage as the union of one man and one woman.”