"What I think religious groups do best is they put people in proximity with one another," he said. "My sense is that it's much more difficult to condemn homosexuality if you know that the son of your best friend in church or someone who worships in the next pew from you is gay."
The Human Rights Campaign, the nation's largest gay rights group, applauded the cathedral's change Wednesday as a milestone.
"Today, the church sent a simple but powerful message to LGBT Episcopalians — you are loved just the way you are, and for that we embrace you," said the Rev. MacArthur Flournoy, the deputy director of HRC's religion and faith program.
The conservative National Organization for Marriage, which opposes same-sex marriage, said the cathedral's change was "disappointing but not surprising," given the direction of the Episcopal Church. In light of the cathedral's national prominence, spokesman Thomas Peters called the marriage announcement "an opportunity for people to wake up to what's happening."
"It reminds us that marriage is really an all or nothing deal," he said. "Does America want to retain its marriage tradition or fundamentally give it up?"
Same-sex marriage is now legal in nine states and the District of Columbia. Legislators in Illinois and Rhode Island are set to take up bills to possibly join them.
The first same-sex wedding performed last month at West Point's Cadet Chapel drew some protests from conservatives. The National Cathedral is even more visible.
Budde, the Episcopal bishop, said there is a long tradition of changing views in the church on racial equality, slavery and the role of women.
"When I was born, girls couldn't be acolytes. Now I'm bishop of one of the largest dioceses in the country," she said.
Budde said the cathedral is confident and certain of its decision but realizes it causes difficulty for other fellow Christians.
"This is a big deal, and we're moving with as much graciousness and humility as we can," she said.
Gay weddings will be allowed immediately. But it will likely be six months to a year before the first marriages are performed due to the cathedral's busy schedule and its pre-marital counseling requirement. Generally, only couples affiliated with the cathedral are eligible.
The cathedral hosts about 16 weddings a year. Church leaders had not received any requests for same-sex weddings ahead of Wednesday's announcement.
Hall said he does not expect any objections within the cathedral congregation, but the change may draw scrutiny from the outside.
He said he sees marriage as a human issue, not a political issue.
"For us to be able to say we embrace same-sex marriage as a tool for faithful people to live their lives as Christian people," he said, "for us to be able to say that at a moment when so many other barriers toward full equality and full inclusion for gay and lesbian people are falling, I think it is an important symbolic moment."
Associated Press National Writer David Crary in New York City contributed to this report.
Washington National Cathedral: http://www.nationalcathedral.org
Follow Brett Zongker on Twitter at https://twitter.com/DCArtBeat