Randall Balmer, a Dartmouth University religion professor and an Episcopal priest who supports the change, said he expects little fallout from the policy within the American church. Most of the most conservative Episcopalians who oppose blessing same-sex relationships have probably already left the church, he said.
"In many ways, the church is tracking public sentiment," which is increasingly supportive of same-sex relationships, Balmer said ahead of Tuesday's vote. "The Episcopal Church is merely part of that trend."
He said it's also unlikely to increase tensions with conservative elements of the worldwide Anglican Communion, of which the Episcopal Church is a member.
"I really don't think it will have a major effect. The real divisions already occurred over Gene Robinson's consecration in 2003," he said.
But some conservatives within the communion might try to use the decision to further marginalize the U.S. church, Balmer said.