A diverse group of Maryland religious leaders launched a coalition Wednesday that organizers vowed would steadfastly resist the legalization of same-sex marriage in the 2012 legislative session.

“We will not lie down in the face of renewed efforts to redefine this institution,” said Derek McCoy, the leader of the new Maryland Marriage Alliance, which held a pair of news conferences at churches in Prince George’s County and Baltimore. “Marriage is defined as between one man and one woman.”