TA Wesley found this article from Reuters about a big development in the Episcopal Church (mentioned briefly in this earlier post). More conservative members of the Episcopal Church are not happy with the direction much of the Episcopal Church has taken, particular with the ordination of gay members to positions in the clergy. The more conservative members see this as a violation of important teachings. As the main body of the Church accommodates such ordinations, the more conservative members see breaking apart from the Church as the only way to continue practicing the religion in the manner they deem best. In general, this is the motivation for new sect formation.
Having a new church arise out of an older one is quite common. Some people in the church see the church going astray from their original teachings and conclude that the best option is to form a new church that more closely matches what they perceive to be an older, more correct version of the church. One interesting aspect of this Episcopal case is that the break-off group still wants to retain a particular official status within the larger Anglican community. That is, they do not want to leave Anglicanism; they just want to form their own version of it in the U.S.
There is a particular logic to this. By retaining certain ties to the original community, they can receive certain benefits that come from inclusion in that community. Put differently, it reduces the costs of separation because members are able to retain more of their religious capital. Receiving that recognition is not automatic, however. A presiding body will vote on whether to accept this new church in the community. If they do not vote in favor, this could potentially affect the success of this new church as some Episcopalians might not be less interested in joining the new group. In the minds of many, this is a risk worth taking.