I wonder if the new heresy will be a confusion of the idea of "catholic". Some people think that it means the church is open to all new movements, that we don't close ourselves off to things. Yet, throughout the history of the church, this is a common theme. From Basil and Tertulian battling early heresies to Gregory the Great's attempt to unite the church under himself, to St. Thomas Aquinas infamous "you have heard it said...but I say" style of Socratic method, the church has had to distance herself from incorrect ideas in order to cleave more closely to Christ.
The Unitarian community in this country will take anyone regardless of what they believe. We are universal, not because you can believe whatever you want or because the church should be open to everything but because we need to communicate Christ to all the world.