Because this site is mainly directed to Protestants in congregational polity churches, I should talk about the church itself a bit before talking about the Independent Sacramental Movement (ISM), to identify differences of focus that might otherwise turn into a confusing blur. I'm also working out of my comfort zone here and in future, so there's probably going to be mistakes, or at least phrasings that those in the ISM wouldn't use. If so, please comment.
(Since the ISM attracts a certain kind of viscous internet troll, I will be applying a heavier than usual editorial hand in approving comments. If you're here to stir up trouble about the ISM, don't bother. This series is not for you.)
The Cambridge Platform of 1648 was a New England response to the Westminster Confession; the main differences were with polity, or the system of church governance, and persists (often in wildly modified forms) in the inheriting churches of New England Congregationalism, which includes the Unitarians and Universalists. So even in these late days, we respect it and go back to its understanding. Chapter two of the platform starts "[t]he catholic church is the whole company of those elected, redeemed, and in time effectively called from the state of sin and death, unto a state of grace and salvation in Jesus Christ." But that's a spiritual state: it doesn't distinguish between the living and the dead; or the past, present or future. A series of no, not that clauses follow leading to the proposition that there is no Church — that is, a single visible organization of living Christians around the world — but churches, particular instances that keep communion (both access to the Lord's table and the disciplines of church cooperation) with one another. Explicitly, "we deny a universal visible church." (chapter 2.4)
Section 6 lays out what a church is: "A Congregational church is by the institution of Christ a part of the militant visible church, consisting of a company of saints by calling, united into one body by a holy covenant, for the public worship of God, and the mutual edification of one another, in the fellowship of the Lord Jesus."
In short, Christ's promise of the life-giving promise of the Holy Spirit leaps the generations and is present in the gathered church. To follow the thought, a group of wholly isolated persons could individually have experience of salvation (I'll leave what that means for now), baptize one another, establish a covenant, elect and ordain "officers" (the elders or ministers, and deacons) and be a fully-formed church. Sounds good to me, as unlikely as that might be.
Among the diversity of the ISM, this certainly stands out: there are three orders of ministry (deacon, priest and bishop) and that these orders are transmitted as a sacrament from generation to generation in a succession of bishops in a line of consecration back to Christ's apostles. Without bishops, there is no access to the other six (maybe more) sacraments, which mediate grace. No doubt the Holy Spirit empowers the consecrations, but even without wading into the ISM views of the constitution of the church, there's a basic difference in concept. In the congregational view, the "faith once delivered unto the saints" (Jude 1:3) is held by the faithful, while in the ISM (as with other churches with apostolic succession) there is a personal continuity. (Which is not to suggest that the laity are optional in the ISM, but that's an issue of the constitution of the church that I'm not qualified to speak about. I would be interested how the Vatican II document, Lumen Gentium has been received.) In congregationalism, at least in its "purest " form, the deacons and ministers fill a role more than experiencing the basic, ontological change of nature as expressed in the ordinations of the ISM. Of course, what's so pure any more? Ideas about the ministry have developed over time, including what might be called (but never is in this way) its mystical constitution. Perhaps I should ask how Lumen Gentium has influenced the Unitarian Universalists, if perhaps through the side door. After all, James Luther Adams was an observer at Vatican II.
Next time, a bit about who the ISM are in the context of the churches in apostolic succession.