We believe with early Baptists and the mainstream Christian tradition that an individual's conscience is inviolable, but not infallible, and therefore we are always under the obligation to see to it that our consciences have been formed by the faithful practices of the church.
Their response begs the question: How do you decide what is accepted as "the faithful practices of the church?" By this criterion, it is hard to comprehend how a people who call themselves Baptists could exist. Baptists were born of a conscientious objection to the long tradition and "faithful practice" of baptising infants. For more than a millenium all of the "spiritual masters" of the church taught the practice.
The communitarians write:
While we reject the authoritarian subjugation of individual conscience, there is a sense in which we do believe in being subject to "spiritual masters" -- but not self-appointed ones.
That we "self-appointed" our "spiritual masters" is a charge that has been levelled against both Anabaptists and Baptists for centuries (Where did John Smyth get the authority to baptise those first English Baptists?). Except for communitarians and Southern Baptists since 1979, most Baptists have not been advocates for apostolic successions and church hierarchies.
The same quotations demonstrate the communitarian's hostility to liberty of conscience. First, they exaggerate the claims of conscience. I know of no Baptists who claim "infallibility" for their conscience. I know many Baptists who acknowledge the authority of conscience under the guidance of the Holy Spirit. Second, they couple the pejorative "subjugation" with conscience when speaking about its authority. Most Baptists don't view the guidance of the Holy Spirit as "subjugation."
There's a lot more with which to quibble, but that should be enough for now. Also, I'm turning the comments section on again and I'll try to make time to respond to comments.