OSSINING, N.Y. — One morning last summer, Connie Knapp got a phone call from her minister. Several days earlier, the Supreme Court had handed down a ruling fortifying the movement for same-sex marriage. Her pastor, the Rev. Chip Low, had a feeling that Ms. Knapp and her partner, Anne Corey, might want to have a wedding.

For going on 30 years, since they had met in a running club and fallen in love over spaghetti with clam sauce at a Chelsea diner, Ms. Knapp and Ms. Corey had considered themselves a couple. Yet even after gay marriage was allowed in New York State, they had vowed not to wed as long as the Defense of Marriage Act remained a federal law.

Now the high court had struck down a key part of the measure, which had denied federal benefits to married same-sex couples. After years of enduring opprobrium from religious conservatives, of being told that gays and lesbians were evil and immoral and intrinsically disordered and had provoked the Almighty to cause 9/11, the women had a friendly minister who had hung the rainbow flag outside his church and was offering to officiate at their ceremony.

There was just one obstacle. Ms. Knapp, born and raised Catholic, was now a Presbyterian studying for the ministry. Ms. Corey was from a Reform Jewish background. The women, both 65, were about to discover that in an era of growing acceptance of gay marriage, they would have no trouble finding clergy members ready to perform a same-sex ceremony. An interfaith ceremony, however, looked like a deal-breaker.