Kelly had been advocating for the ordination of women in the Church of Jesus Christ of Latter-day Saints. She co-founded the group Ordain Women to spread her reform message, and it was for this work -- or at least the character of it -- that she found herself facing a charge of apostasy.
She had previously been put on "probation," but the reformer refused to take down the Ordain Women website.
Kelly was informed of her fate by an official letter from Mark Harrison, her bishop in Oakton, Virginia. The letter was delivered via email. Kelly received it in Utah, where she moved earlier this month.
"The difficulty, Sister Kelly, is not that you say you have questions or even that you believe that women should receive the priesthood," Harrison wrote. "The problem is that you have persisted in an aggressive effort to persuade other Church members to your point of view and that your course of action has threatened to erode the faith of others."
Although the excommunication is not permanent -- and leaves open to possibility of reconciliation -- Kelly, a former Washington human rights attorney, said the decision effectively severed her ties with the community and forced her to uproot her family.
"These conditions almost always last at least one year," the letter warned. Only if Kelly agreed to abandon advocacy work and teachings that "undermine the Church, its leaders, and the doctrine of the priesthood" could she then be readmitted.
"Today is a tragic day for my family and me as we process the many ways this will impact us, both in this life and in the eternities," Kelly said in a statement.
Kelly's is the latest in a string of high profile excommunication hearings. Up next, John Dehlin -- a prominent reformer who faces similar charges for his advocacy for gay rights and acceptance within the Mormon community.