"Let's be careful about the concept of social evolution," said the Rev. Leonard Klein, a Roman Catholic priest speaking on behalf of the bishop of the Diocese of Wilmington, which serves more than 200,000 Catholics in Delaware and Maryland's Eastern Shore.
"When you remove male and female from the definition of marriage, all bets are off," added Klein, who urged lawmakers to show an "appropriate humility" for thousands of years of human experience.
Under the bill, no new civil unions will be performed in Delaware after July 1, and existing civil unions will be converted to marriages over the next year. The legislation also states that same-sex unions established in other states will be treated the same as marriages under Delaware law.
The bill does not force clerics to perform same-sex marriages that conflict with their religious beliefs. But under an existing Delaware law banning discrimination based on sexual orientation, business owners who refuse to provide marriage-related services to same-sex couples for reasons of conscience could be subject to discrimination claims.
Delaware joins neighboring Maryland and the nearby District of Columbia as jurisdictions that have approved gay marriage. Last week, Rhode Island became the 10th state to allow gay and lesbian couples to wed, with independent Gov. Lincoln Chafee signing the bill an hour after its final passage.
Minnesota appeared poised to legalize gay marriage after the Democratic speaker of the state House said Tuesday that a gay marriage bill endorsed by the governor and likely to pass in the state Senate also now has enough backing in his chamber. The House will vote on the measure Thursday, and if it passes, the Democratic-led Senate could vote on it as soon as Saturday.