Fr. Raniero Cantalamessa is the preacher for the papal household at the Vatican. In this sermon for the 4th sunday of Easter, he warns against the influence of sects: Sheep that go astray. Though the current Pope is often thought to be a conservative, especially on ecclesiological and liturgical matters, his official preacher refrains from assigning the sectarian label to all Christians outside the Roman fold:
When we speak of sects, we must be careful not to put everything on the same level. Protestant evangelicals and Pentecostals, for example, apart from isolated groups, are not sects. For years the Catholic Church has maintained an official dialogue with them, something that it would never do with sects.
The true sects can be recognized by certain characteristics. First of all, in regard to their creed, they do not share essential points with the Christian faith, such as the divinity of Christ and the Trinity; or rather they mix foreign and incompatible elements with Christian doctrines -- re-incarnation, for example. In regard to methods, they are literally “sheep stealers” in the sense that they try to take the faithful away from their Church of origin, to make them followers of their sect.
The other day one of my colleagues alerted me to this group: the Canadian Centre for Progressive Christianity. Judging from Gretta Vosper's account of what her group believes — or rather, does not believe — it is safe to say that it would quite nicely qualify as a sect, using Fr. Cantalamessa's criteria. One assumes then that a Catholic-Progressive Christian dialogue will not be convened any time soon.