Durham, N.H. ? Today’s consecration of the first openly gay Episcopal bishop will be a watershed moment for American religion that will crystallize severe divisions over homosexuality among Episcopalians and their fellow Anglicans worldwide.

With the elevation of the Rev. V. Gene Robinson, the Episcopal Church will become the first major Christian denomination anywhere to choose a bishop living openly with a same-sex partner.

Reverberations from that decision will last for years, and some consequences will shake out immediately.

The split will even be evident in the venerable consecration ritual, when the congregation is asked if there is “any reason why we should not proceed.” New Hampshire conservatives are expected to register objections.

And as the ceremony proceeds in a University of New Hampshire arena, opponents of Robinson’s consecration will conduct a competing Communion service at a nearby church. Others plan candlelight vigils.

The Episcopalians’ most dangerous division is within their hierarchy.

About 50 bishops will attend today’s ceremony and register their support for Robinson. Presiding Bishop Frank Griswold and his predecessor as head of the Episcopal Church will be among those laying hands on Robinson to make him a bishop.

But assistant Bishop David Bena of Albany, N.Y., plans to rise to read a protest from the Conference of North American Anglican Bishops, formed only Monday.

“This threatens to be the most severe break ever within the American Episcopal Church,” says the Rev. Charles Henery, a church historian who opposes Robinson’s elevation.

The societal implications are equally historic.

“For countless centuries, gay and lesbian people have been on the fringes of society,” said Robinson, who is joining the leadership of a denomination that has long epitomized social status in America.

Robinson’s consecration is especially important because churches have long been a powerful force against acceptance of same-sex behavior, says Louie Crew, a pioneering Episcopal gay activist. For many years, it was gays demonstrating outside Christian denominational meetings.

In a pointed affirmation of the gay cause, Robinson invited Crew, a second homosexual activist and his own partner — as well as his ex-wife and their two daughters — to join those who will ritually present him Sunday.

In the long term, Crew predicts, thousands of homosexuals and open-minded heterosexuals will flow into the denomination, whose membership has declined substantially and now stands at 2.3 million.